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gh-basher83-lunar-claude-pl…/skills/claude-agent-sdk/references/api-reference.md
2025-11-29 18:00:18 +08:00

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# Agent SDK reference - Python
> Complete API reference for the Python Agent SDK, including all functions, types, and classes.
## Installation
```bash theme={null}
pip install claude-agent-sdk
```
## Choosing Between `query()` and `ClaudeSDKClient`
The Python SDK provides two ways to interact with Claude Code:
### Quick Comparison
| Feature | `query()` | `ClaudeSDKClient` |
| :------------------ | :---------------------------- | :--------------------------------- |
| **Session** | Creates new session each time | Reuses same session |
| **Conversation** | Single exchange | Multiple exchanges in same context |
| **Connection** | Managed automatically | Manual control |
| **Streaming Input** | ✅ Supported | ✅ Supported |
| **Interrupts** | ❌ Not supported | ✅ Supported |
| **Hooks** | ❌ Not supported | ✅ Supported |
| **Custom Tools** | ❌ Not supported | ✅ Supported |
| **Continue Chat** | ❌ New session each time | ✅ Maintains conversation |
| **Use Case** | One-off tasks | Continuous conversations |
### When to Use `query()` (New Session Each Time)
**Best for:**
* One-off questions where you don't need conversation history
* Independent tasks that don't require context from previous exchanges
* Simple automation scripts
* When you want a fresh start each time
### When to Use `ClaudeSDKClient` (Continuous Conversation)
**Best for:**
* **Continuing conversations** - When you need Claude to remember context
* **Follow-up questions** - Building on previous responses
* **Interactive applications** - Chat interfaces, REPLs
* **Response-driven logic** - When next action depends on Claude's response
* **Session control** - Managing conversation lifecycle explicitly
## Functions
### `query()`
Creates a new session for each interaction with Claude Code. Returns an async iterator that yields messages as they arrive. Each call to `query()` starts fresh with no memory of previous interactions.
```python theme={null}
async def query(
*,
prompt: str | AsyncIterable[dict[str, Any]],
options: ClaudeAgentOptions | None = None
) -> AsyncIterator[Message]
```
#### Parameters
| Parameter | Type | Description |
| :-------- | :--------------------------- | :------------------------------------------------------------------------- |
| `prompt` | `str \| AsyncIterable[dict]` | The input prompt as a string or async iterable for streaming mode |
| `options` | `ClaudeAgentOptions \| None` | Optional configuration object (defaults to `ClaudeAgentOptions()` if None) |
#### Returns
Returns an `AsyncIterator[Message]` that yields messages from the conversation.
#### Example - With options
```python theme={null}
import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions
async def main():
options = ClaudeAgentOptions(
system_prompt="You are an expert Python developer",
permission_mode='acceptEdits',
cwd="/home/user/project"
)
async for message in query(
prompt="Create a Python web server",
options=options
):
print(message)
asyncio.run(main())
```
### `tool()`
Decorator for defining MCP tools with type safety.
```python theme={null}
def tool(
name: str,
description: str,
input_schema: type | dict[str, Any]
) -> Callable[[Callable[[Any], Awaitable[dict[str, Any]]]], SdkMcpTool[Any]]
```
#### Parameters
| Parameter | Type | Description |
| :------------- | :----------------------- | :------------------------------------------------------ |
| `name` | `str` | Unique identifier for the tool |
| `description` | `str` | Human-readable description of what the tool does |
| `input_schema` | `type \| dict[str, Any]` | Schema defining the tool's input parameters (see below) |
#### Input Schema Options
1. **Simple type mapping** (recommended):
```python theme={null}
{"text": str, "count": int, "enabled": bool}
```
2. **JSON Schema format** (for complex validation):
```python theme={null}
{
"type": "object",
"properties": {
"text": {"type": "string"},
"count": {"type": "integer", "minimum": 0}
},
"required": ["text"]
}
```
#### Returns
A decorator function that wraps the tool implementation and returns an `SdkMcpTool` instance.
#### Example
```python theme={null}
from claude_agent_sdk import tool
from typing import Any
@tool("greet", "Greet a user", {"name": str})
async def greet(args: dict[str, Any]) -> dict[str, Any]:
return {
"content": [{
"type": "text",
"text": f"Hello, {args['name']}!"
}]
}
```
### `create_sdk_mcp_server()`
Create an in-process MCP server that runs within your Python application.
```python theme={null}
def create_sdk_mcp_server(
name: str,
version: str = "1.0.0",
tools: list[SdkMcpTool[Any]] | None = None
) -> McpSdkServerConfig
```
#### Parameters
| Parameter | Type | Default | Description |
| :-------- | :------------------------------ | :-------- | :---------------------------------------------------- |
| `name` | `str` | - | Unique identifier for the server |
| `version` | `str` | `"1.0.0"` | Server version string |
| `tools` | `list[SdkMcpTool[Any]] \| None` | `None` | List of tool functions created with `@tool` decorator |
#### Returns
Returns an `McpSdkServerConfig` object that can be passed to `ClaudeAgentOptions.mcp_servers`.
#### Example
```python theme={null}
from claude_agent_sdk import tool, create_sdk_mcp_server
@tool("add", "Add two numbers", {"a": float, "b": float})
async def add(args):
return {
"content": [{
"type": "text",
"text": f"Sum: {args['a'] + args['b']}"
}]
}
@tool("multiply", "Multiply two numbers", {"a": float, "b": float})
async def multiply(args):
return {
"content": [{
"type": "text",
"text": f"Product: {args['a'] * args['b']}"
}]
}
calculator = create_sdk_mcp_server(
name="calculator",
version="2.0.0",
tools=[add, multiply] # Pass decorated functions
)
# Use with Claude
options = ClaudeAgentOptions(
mcp_servers={"calc": calculator},
allowed_tools=["mcp__calc__add", "mcp__calc__multiply"]
)
```
## Classes
### `ClaudeSDKClient`
**Maintains a conversation session across multiple exchanges.** This is the Python equivalent of how the TypeScript SDK's `query()` function works internally - it creates a client object that can continue conversations.
#### Key Features
* **Session Continuity**: Maintains conversation context across multiple `query()` calls
* **Same Conversation**: Claude remembers previous messages in the session
* **Interrupt Support**: Can stop Claude mid-execution
* **Explicit Lifecycle**: You control when the session starts and ends
* **Response-driven Flow**: Can react to responses and send follow-ups
* **Custom Tools & Hooks**: Supports custom tools (created with `@tool` decorator) and hooks
```python theme={null}
class ClaudeSDKClient:
def __init__(self, options: ClaudeAgentOptions | None = None)
async def connect(self, prompt: str | AsyncIterable[dict] | None = None) -> None
async def query(self, prompt: str | AsyncIterable[dict], session_id: str = "default") -> None
async def receive_messages(self) -> AsyncIterator[Message]
async def receive_response(self) -> AsyncIterator[Message]
async def interrupt(self) -> None
async def disconnect(self) -> None
```
#### Methods
| Method | Description |
| :-------------------------- | :------------------------------------------------------------------ |
| `__init__(options)` | Initialize the client with optional configuration |
| `connect(prompt)` | Connect to Claude with an optional initial prompt or message stream |
| `query(prompt, session_id)` | Send a new request in streaming mode |
| `receive_messages()` | Receive all messages from Claude as an async iterator |
| `receive_response()` | Receive messages until and including a ResultMessage |
| `interrupt()` | Send interrupt signal (only works in streaming mode) |
| `disconnect()` | Disconnect from Claude |
#### Context Manager Support
The client can be used as an async context manager for automatic connection management:
```python theme={null}
async with ClaudeSDKClient() as client:
await client.query("Hello Claude")
async for message in client.receive_response():
print(message)
```
> **Important:** When iterating over messages, avoid using `break` to exit early as this can cause asyncio cleanup issues. Instead, let the iteration complete naturally or use flags to track when you've found what you need.
#### Example - Continuing a conversation
```python theme={null}
import asyncio
from claude_agent_sdk import ClaudeSDKClient, AssistantMessage, TextBlock, ResultMessage
async def main():
async with ClaudeSDKClient() as client:
# First question
await client.query("What's the capital of France?")
# Process response
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Claude: {block.text}")
# Follow-up question - Claude remembers the previous context
await client.query("What's the population of that city?")
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Claude: {block.text}")
# Another follow-up - still in the same conversation
await client.query("What are some famous landmarks there?")
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Claude: {block.text}")
asyncio.run(main())
```
#### Example - Streaming input with ClaudeSDKClient
```python theme={null}
import asyncio
from claude_agent_sdk import ClaudeSDKClient
async def message_stream():
"""Generate messages dynamically."""
yield {"type": "text", "text": "Analyze the following data:"}
await asyncio.sleep(0.5)
yield {"type": "text", "text": "Temperature: 25°C"}
await asyncio.sleep(0.5)
yield {"type": "text", "text": "Humidity: 60%"}
await asyncio.sleep(0.5)
yield {"type": "text", "text": "What patterns do you see?"}
async def main():
async with ClaudeSDKClient() as client:
# Stream input to Claude
await client.query(message_stream())
# Process response
async for message in client.receive_response():
print(message)
# Follow-up in same session
await client.query("Should we be concerned about these readings?")
async for message in client.receive_response():
print(message)
asyncio.run(main())
```
#### Example - Using interrupts
```python theme={null}
import asyncio
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions
async def interruptible_task():
options = ClaudeAgentOptions(
allowed_tools=["Bash"],
permission_mode="acceptEdits"
)
async with ClaudeSDKClient(options=options) as client:
# Start a long-running task
await client.query("Count from 1 to 100 slowly")
# Let it run for a bit
await asyncio.sleep(2)
# Interrupt the task
await client.interrupt()
print("Task interrupted!")
# Send a new command
await client.query("Just say hello instead")
async for message in client.receive_response():
# Process the new response
pass
asyncio.run(interruptible_task())
```
#### Example - Advanced permission control
```python theme={null}
from claude_agent_sdk import (
ClaudeSDKClient,
ClaudeAgentOptions
)
async def custom_permission_handler(
tool_name: str,
input_data: dict,
context: dict
):
"""Custom logic for tool permissions."""
# Block writes to system directories
if tool_name == "Write" and input_data.get("file_path", "").startswith("/system/"):
return {
"behavior": "deny",
"message": "System directory write not allowed",
"interrupt": True
}
# Redirect sensitive file operations
if tool_name in ["Write", "Edit"] and "config" in input_data.get("file_path", ""):
safe_path = f"./sandbox/{input_data['file_path']}"
return {
"behavior": "allow",
"updatedInput": {**input_data, "file_path": safe_path}
}
# Allow everything else
return {
"behavior": "allow",
"updatedInput": input_data
}
async def main():
options = ClaudeAgentOptions(
can_use_tool=custom_permission_handler,
allowed_tools=["Read", "Write", "Edit"]
)
async with ClaudeSDKClient(options=options) as client:
await client.query("Update the system config file")
async for message in client.receive_response():
# Will use sandbox path instead
print(message)
asyncio.run(main())
```
## Types
### `SdkMcpTool`
Definition for an SDK MCP tool created with the `@tool` decorator.
```python theme={null}
@dataclass
class SdkMcpTool(Generic[T]):
name: str
description: str
input_schema: type[T] | dict[str, Any]
handler: Callable[[T], Awaitable[dict[str, Any]]]
```
| Property | Type | Description |
| :------------- | :----------------------------------------- | :----------------------------------------- |
| `name` | `str` | Unique identifier for the tool |
| `description` | `str` | Human-readable description |
| `input_schema` | `type[T] \| dict[str, Any]` | Schema for input validation |
| `handler` | `Callable[[T], Awaitable[dict[str, Any]]]` | Async function that handles tool execution |
### `ClaudeAgentOptions`
Configuration dataclass for Claude Code queries.
```python theme={null}
@dataclass
class ClaudeAgentOptions:
allowed_tools: list[str] = field(default_factory=list)
system_prompt: str | SystemPromptPreset | None = None
mcp_servers: dict[str, McpServerConfig] | str | Path = field(default_factory=dict)
permission_mode: PermissionMode | None = None
continue_conversation: bool = False
resume: str | None = None
max_turns: int | None = None
disallowed_tools: list[str] = field(default_factory=list)
model: str | None = None
permission_prompt_tool_name: str | None = None
cwd: str | Path | None = None
settings: str | None = None
add_dirs: list[str | Path] = field(default_factory=list)
env: dict[str, str] = field(default_factory=dict)
extra_args: dict[str, str | None] = field(default_factory=dict)
max_buffer_size: int | None = None
debug_stderr: Any = sys.stderr # Deprecated
stderr: Callable[[str], None] | None = None
can_use_tool: CanUseTool | None = None
hooks: dict[HookEvent, list[HookMatcher]] | None = None
user: str | None = None
include_partial_messages: bool = False
fork_session: bool = False
agents: dict[str, AgentDefinition] | None = None
setting_sources: list[SettingSource] | None = None
```
| Property | Type | Default | Description |
| :---------------------------- | :------------------------------------------- | :------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `allowed_tools` | `list[str]` | `[]` | List of allowed tool names |
| `system_prompt` | `str \| SystemPromptPreset \| None` | `None` | System prompt configuration. Pass a string for custom prompt, or use `{"type": "preset", "preset": "claude_code"}` for Claude Code's system prompt. Add `"append"` to extend the preset |
| `mcp_servers` | `dict[str, McpServerConfig] \| str \| Path` | `{}` | MCP server configurations or path to config file |
| `permission_mode` | `PermissionMode \| None` | `None` | Permission mode for tool usage |
| `continue_conversation` | `bool` | `False` | Continue the most recent conversation |
| `resume` | `str \| None` | `None` | Session ID to resume |
| `max_turns` | `int \| None` | `None` | Maximum conversation turns |
| `disallowed_tools` | `list[str]` | `[]` | List of disallowed tool names |
| `model` | `str \| None` | `None` | Claude model to use |
| `permission_prompt_tool_name` | `str \| None` | `None` | MCP tool name for permission prompts |
| `cwd` | `str \| Path \| None` | `None` | Current working directory |
| `settings` | `str \| None` | `None` | Path to settings file |
| `add_dirs` | `list[str \| Path]` | `[]` | Additional directories Claude can access |
| `env` | `dict[str, str]` | `{}` | Environment variables |
| `extra_args` | `dict[str, str \| None]` | `{}` | Additional CLI arguments to pass directly to the CLI |
| `max_buffer_size` | `int \| None` | `None` | Maximum bytes when buffering CLI stdout |
| `debug_stderr` | `Any` | `sys.stderr` | *Deprecated* - File-like object for debug output. Use `stderr` callback instead |
| `stderr` | `Callable[[str], None] \| None` | `None` | Callback function for stderr output from CLI |
| `can_use_tool` | `CanUseTool \| None` | `None` | Tool permission callback function |
| `hooks` | `dict[HookEvent, list[HookMatcher]] \| None` | `None` | Hook configurations for intercepting events |
| `user` | `str \| None` | `None` | User identifier |
| `include_partial_messages` | `bool` | `False` | Include partial message streaming events |
| `fork_session` | `bool` | `False` | When resuming with `resume`, fork to a new session ID instead of continuing the original session |
| `agents` | `dict[str, AgentDefinition] \| None` | `None` | Programmatically defined subagents |
| `plugins` | `list[SdkPluginConfig]` | `[]` | Load custom plugins from local paths. See [Plugins](/en/api/agent-sdk/plugins) for details |
| `setting_sources` | `list[SettingSource] \| None` | `None` (no settings) | Control which filesystem settings to load. When omitted, no settings are loaded. **Note:** Must include `"project"` to load CLAUDE.md files |
### `SystemPromptPreset`
Configuration for using Claude Code's preset system prompt with optional additions.
```python theme={null}
class SystemPromptPreset(TypedDict):
type: Literal["preset"]
preset: Literal["claude_code"]
append: NotRequired[str]
```
| Field | Required | Description |
| :------- | :------- | :------------------------------------------------------------ |
| `type` | Yes | Must be `"preset"` to use a preset system prompt |
| `preset` | Yes | Must be `"claude_code"` to use Claude Code's system prompt |
| `append` | No | Additional instructions to append to the preset system prompt |
### `SettingSource`
Controls which filesystem-based configuration sources the SDK loads settings from.
```python theme={null}
SettingSource = Literal["user", "project", "local"]
```
| Value | Description | Location |
| :---------- | :------------------------------------------- | :---------------------------- |
| `"user"` | Global user settings | `~/.claude/settings.json` |
| `"project"` | Shared project settings (version controlled) | `.claude/settings.json` |
| `"local"` | Local project settings (gitignored) | `.claude/settings.local.json` |
#### Default behavior
When `setting_sources` is **omitted** or **`None`**, the SDK does **not** load any filesystem settings. This provides isolation for SDK applications.
#### Why use setting\_sources?
**Load all filesystem settings (legacy behavior):**
```python theme={null}
# Load all settings like SDK v0.0.x did
from claude_agent_sdk import query, ClaudeAgentOptions
async for message in query(
prompt="Analyze this code",
options=ClaudeAgentOptions(
setting_sources=["user", "project", "local"] # Load all settings
)
):
print(message)
```
**Load only specific setting sources:**
```python theme={null}
# Load only project settings, ignore user and local
async for message in query(
prompt="Run CI checks",
options=ClaudeAgentOptions(
setting_sources=["project"] # Only .claude/settings.json
)
):
print(message)
```
**Testing and CI environments:**
```python theme={null}
# Ensure consistent behavior in CI by excluding local settings
async for message in query(
prompt="Run tests",
options=ClaudeAgentOptions(
setting_sources=["project"], # Only team-shared settings
permission_mode="bypassPermissions"
)
):
print(message)
```
**SDK-only applications:**
```python theme={null}
# Define everything programmatically (default behavior)
# No filesystem dependencies - setting_sources defaults to None
async for message in query(
prompt="Review this PR",
options=ClaudeAgentOptions(
# setting_sources=None is the default, no need to specify
agents={ /* ... */ },
mcp_servers={ /* ... */ },
allowed_tools=["Read", "Grep", "Glob"]
)
):
print(message)
```
**Loading CLAUDE.md project instructions:**
```python theme={null}
# Load project settings to include CLAUDE.md files
async for message in query(
prompt="Add a new feature following project conventions",
options=ClaudeAgentOptions(
system_prompt={
"type": "preset",
"preset": "claude_code" # Use Claude Code's system prompt
},
setting_sources=["project"], # Required to load CLAUDE.md from project
allowed_tools=["Read", "Write", "Edit"]
)
):
print(message)
```
#### Settings precedence
When multiple sources are loaded, settings are merged with this precedence (highest to lowest):
1. Local settings (`.claude/settings.local.json`)
2. Project settings (`.claude/settings.json`)
3. User settings (`~/.claude/settings.json`)
Programmatic options (like `agents`, `allowed_tools`) always override filesystem settings.
### `AgentDefinition`
Configuration for a subagent defined programmatically.
```python theme={null}
@dataclass
class AgentDefinition:
description: str
prompt: str
tools: list[str] | None = None
model: Literal["sonnet", "opus", "haiku", "inherit"] | None = None
```
| Field | Required | Description |
| :------------ | :------- | :------------------------------------------------------------- |
| `description` | Yes | Natural language description of when to use this agent |
| `tools` | No | Array of allowed tool names. If omitted, inherits all tools |
| `prompt` | Yes | The agent's system prompt |
| `model` | No | Model override for this agent. If omitted, uses the main model |
### `PermissionMode`
Permission modes for controlling tool execution.
```python theme={null}
PermissionMode = Literal[
"default", # Standard permission behavior
"acceptEdits", # Auto-accept file edits
"plan", # Planning mode - no execution
"bypassPermissions" # Bypass all permission checks (use with caution)
]
```
### `McpSdkServerConfig`
Configuration for SDK MCP servers created with `create_sdk_mcp_server()`.
```python theme={null}
class McpSdkServerConfig(TypedDict):
type: Literal["sdk"]
name: str
instance: Any # MCP Server instance
```
### `McpServerConfig`
Union type for MCP server configurations.
```python theme={null}
McpServerConfig = McpStdioServerConfig | McpSSEServerConfig | McpHttpServerConfig | McpSdkServerConfig
```
#### `McpStdioServerConfig`
```python theme={null}
class McpStdioServerConfig(TypedDict):
type: NotRequired[Literal["stdio"]] # Optional for backwards compatibility
command: str
args: NotRequired[list[str]]
env: NotRequired[dict[str, str]]
```
#### `McpSSEServerConfig`
```python theme={null}
class McpSSEServerConfig(TypedDict):
type: Literal["sse"]
url: str
headers: NotRequired[dict[str, str]]
```
#### `McpHttpServerConfig`
```python theme={null}
class McpHttpServerConfig(TypedDict):
type: Literal["http"]
url: str
headers: NotRequired[dict[str, str]]
```
### `SdkPluginConfig`
Configuration for loading plugins in the SDK.
```python theme={null}
class SdkPluginConfig(TypedDict):
type: Literal["local"]
path: str
```
| Field | Type | Description |
| :----- | :----------------- | :--------------------------------------------------------- |
| `type` | `Literal["local"]` | Must be `"local"` (only local plugins currently supported) |
| `path` | `str` | Absolute or relative path to the plugin directory |
**Example:**
```python theme={null}
plugins=[
{"type": "local", "path": "./my-plugin"},
{"type": "local", "path": "/absolute/path/to/plugin"}
]
```
For complete information on creating and using plugins, see [Plugins](/en/api/agent-sdk/plugins).
## Message Types
### `Message`
Union type of all possible messages.
```python theme={null}
Message = UserMessage | AssistantMessage | SystemMessage | ResultMessage
```
### `UserMessage`
User input message.
```python theme={null}
@dataclass
class UserMessage:
content: str | list[ContentBlock]
```
### `AssistantMessage`
Assistant response message with content blocks.
```python theme={null}
@dataclass
class AssistantMessage:
content: list[ContentBlock]
model: str
```
### `SystemMessage`
System message with metadata.
```python theme={null}
@dataclass
class SystemMessage:
subtype: str
data: dict[str, Any]
```
### `ResultMessage`
Final result message with cost and usage information.
```python theme={null}
@dataclass
class ResultMessage:
subtype: str
duration_ms: int
duration_api_ms: int
is_error: bool
num_turns: int
session_id: str
total_cost_usd: float | None = None
usage: dict[str, Any] | None = None
result: str | None = None
```
## Content Block Types
### `ContentBlock`
Union type of all content blocks.
```python theme={null}
ContentBlock = TextBlock | ThinkingBlock | ToolUseBlock | ToolResultBlock
```
### `TextBlock`
Text content block.
```python theme={null}
@dataclass
class TextBlock:
text: str
```
### `ThinkingBlock`
Thinking content block (for models with thinking capability).
```python theme={null}
@dataclass
class ThinkingBlock:
thinking: str
signature: str
```
### `ToolUseBlock`
Tool use request block.
```python theme={null}
@dataclass
class ToolUseBlock:
id: str
name: str
input: dict[str, Any]
```
### `ToolResultBlock`
Tool execution result block.
```python theme={null}
@dataclass
class ToolResultBlock:
tool_use_id: str
content: str | list[dict[str, Any]] | None = None
is_error: bool | None = None
```
## Error Types
### `ClaudeSDKError`
Base exception class for all SDK errors.
```python theme={null}
class ClaudeSDKError(Exception):
"""Base error for Claude SDK."""
```
### `CLINotFoundError`
Raised when Claude Code CLI is not installed or not found.
```python theme={null}
class CLINotFoundError(CLIConnectionError):
def __init__(self, message: str = "Claude Code not found", cli_path: str | None = None):
"""
Args:
message: Error message (default: "Claude Code not found")
cli_path: Optional path to the CLI that was not found
"""
```
### `CLIConnectionError`
Raised when connection to Claude Code fails.
```python theme={null}
class CLIConnectionError(ClaudeSDKError):
"""Failed to connect to Claude Code."""
```
### `ProcessError`
Raised when the Claude Code process fails.
```python theme={null}
class ProcessError(ClaudeSDKError):
def __init__(self, message: str, exit_code: int | None = None, stderr: str | None = None):
self.exit_code = exit_code
self.stderr = stderr
```
### `CLIJSONDecodeError`
Raised when JSON parsing fails.
```python theme={null}
class CLIJSONDecodeError(ClaudeSDKError):
def __init__(self, line: str, original_error: Exception):
"""
Args:
line: The line that failed to parse
original_error: The original JSON decode exception
"""
self.line = line
self.original_error = original_error
```
## Hook Types
### `HookEvent`
Supported hook event types. Note that due to setup limitations, the Python SDK does not support SessionStart, SessionEnd, and Notification hooks.
```python theme={null}
HookEvent = Literal[
"PreToolUse", # Called before tool execution
"PostToolUse", # Called after tool execution
"UserPromptSubmit", # Called when user submits a prompt
"Stop", # Called when stopping execution
"SubagentStop", # Called when a subagent stops
"PreCompact" # Called before message compaction
]
```
### `HookCallback`
Type definition for hook callback functions.
```python theme={null}
HookCallback = Callable[
[dict[str, Any], str | None, HookContext],
Awaitable[dict[str, Any]]
]
```
Parameters:
* `input_data`: Hook-specific input data (see [hook documentation](https://docs.claude.com/en/docs/claude-code/hooks#hook-input))
* `tool_use_id`: Optional tool use identifier (for tool-related hooks)
* `context`: Hook context with additional information
Returns a dictionary that may contain:
* `decision`: `"block"` to block the action
* `systemMessage`: System message to add to the transcript
* `hookSpecificOutput`: Hook-specific output data
### `HookContext`
Context information passed to hook callbacks.
```python theme={null}
@dataclass
class HookContext:
signal: Any | None = None # Future: abort signal support
```
### `HookMatcher`
Configuration for matching hooks to specific events or tools.
```python theme={null}
@dataclass
class HookMatcher:
matcher: str | None = None # Tool name or pattern to match (e.g., "Bash", "Write|Edit")
hooks: list[HookCallback] = field(default_factory=list) # List of callbacks to execute
```
### Hook Usage Example
```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions, HookMatcher, HookContext
from typing import Any
async def validate_bash_command(
input_data: dict[str, Any],
tool_use_id: str | None,
context: HookContext
) -> dict[str, Any]:
"""Validate and potentially block dangerous bash commands."""
if input_data['tool_name'] == 'Bash':
command = input_data['tool_input'].get('command', '')
if 'rm -rf /' in command:
return {
'hookSpecificOutput': {
'hookEventName': 'PreToolUse',
'permissionDecision': 'deny',
'permissionDecisionReason': 'Dangerous command blocked'
}
}
return {}
async def log_tool_use(
input_data: dict[str, Any],
tool_use_id: str | None,
context: HookContext
) -> dict[str, Any]:
"""Log all tool usage for auditing."""
print(f"Tool used: {input_data.get('tool_name')}")
return {}
options = ClaudeAgentOptions(
hooks={
'PreToolUse': [
HookMatcher(matcher='Bash', hooks=[validate_bash_command]),
HookMatcher(hooks=[log_tool_use]) # Applies to all tools
],
'PostToolUse': [
HookMatcher(hooks=[log_tool_use])
]
}
)
async for message in query(
prompt="Analyze this codebase",
options=options
):
print(message)
```
## Tool Input/Output Types
Documentation of input/output schemas for all built-in Claude Code tools. While the Python SDK doesn't export these as types, they represent the structure of tool inputs and outputs in messages.
### Task
**Tool name:** `Task`
**Input:**
```python theme={null}
{
"description": str, # A short (3-5 word) description of the task
"prompt": str, # The task for the agent to perform
"subagent_type": str # The type of specialized agent to use
}
```
**Output:**
```python theme={null}
{
"result": str, # Final result from the subagent
"usage": dict | None, # Token usage statistics
"total_cost_usd": float | None, # Total cost in USD
"duration_ms": int | None # Execution duration in milliseconds
}
```
### Bash
**Tool name:** `Bash`
**Input:**
```python theme={null}
{
"command": str, # The command to execute
"timeout": int | None, # Optional timeout in milliseconds (max 600000)
"description": str | None, # Clear, concise description (5-10 words)
"run_in_background": bool | None # Set to true to run in background
}
```
**Output:**
```python theme={null}
{
"output": str, # Combined stdout and stderr output
"exitCode": int, # Exit code of the command
"killed": bool | None, # Whether command was killed due to timeout
"shellId": str | None # Shell ID for background processes
}
```
### Edit
**Tool name:** `Edit`
**Input:**
```python theme={null}
{
"file_path": str, # The absolute path to the file to modify
"old_string": str, # The text to replace
"new_string": str, # The text to replace it with
"replace_all": bool | None # Replace all occurrences (default False)
}
```
**Output:**
```python theme={null}
{
"message": str, # Confirmation message
"replacements": int, # Number of replacements made
"file_path": str # File path that was edited
}
```
### Read
**Tool name:** `Read`
**Input:**
```python theme={null}
{
"file_path": str, # The absolute path to the file to read
"offset": int | None, # The line number to start reading from
"limit": int | None # The number of lines to read
}
```
**Output (Text files):**
```python theme={null}
{
"content": str, # File contents with line numbers
"total_lines": int, # Total number of lines in file
"lines_returned": int # Lines actually returned
}
```
**Output (Images):**
```python theme={null}
{
"image": str, # Base64 encoded image data
"mime_type": str, # Image MIME type
"file_size": int # File size in bytes
}
```
### Write
**Tool name:** `Write`
**Input:**
```python theme={null}
{
"file_path": str, # The absolute path to the file to write
"content": str # The content to write to the file
}
```
**Output:**
```python theme={null}
{
"message": str, # Success message
"bytes_written": int, # Number of bytes written
"file_path": str # File path that was written
}
```
### Glob
**Tool name:** `Glob`
**Input:**
```python theme={null}
{
"pattern": str, # The glob pattern to match files against
"path": str | None # The directory to search in (defaults to cwd)
}
```
**Output:**
```python theme={null}
{
"matches": list[str], # Array of matching file paths
"count": int, # Number of matches found
"search_path": str # Search directory used
}
```
### Grep
**Tool name:** `Grep`
**Input:**
```python theme={null}
{
"pattern": str, # The regular expression pattern
"path": str | None, # File or directory to search in
"glob": str | None, # Glob pattern to filter files
"type": str | None, # File type to search
"output_mode": str | None, # "content", "files_with_matches", or "count"
"-i": bool | None, # Case insensitive search
"-n": bool | None, # Show line numbers
"-B": int | None, # Lines to show before each match
"-A": int | None, # Lines to show after each match
"-C": int | None, # Lines to show before and after
"head_limit": int | None, # Limit output to first N lines/entries
"multiline": bool | None # Enable multiline mode
}
```
**Output (content mode):**
```python theme={null}
{
"matches": [
{
"file": str,
"line_number": int | None,
"line": str,
"before_context": list[str] | None,
"after_context": list[str] | None
}
],
"total_matches": int
}
```
**Output (files\_with\_matches mode):**
```python theme={null}
{
"files": list[str], # Files containing matches
"count": int # Number of files with matches
}
```
### NotebookEdit
**Tool name:** `NotebookEdit`
**Input:**
```python theme={null}
{
"notebook_path": str, # Absolute path to the Jupyter notebook
"cell_id": str | None, # The ID of the cell to edit
"new_source": str, # The new source for the cell
"cell_type": "code" | "markdown" | None, # The type of the cell
"edit_mode": "replace" | "insert" | "delete" | None # Edit operation type
}
```
**Output:**
```python theme={null}
{
"message": str, # Success message
"edit_type": "replaced" | "inserted" | "deleted", # Type of edit performed
"cell_id": str | None, # Cell ID that was affected
"total_cells": int # Total cells in notebook after edit
}
```
### WebFetch
**Tool name:** `WebFetch`
**Input:**
```python theme={null}
{
"url": str, # The URL to fetch content from
"prompt": str # The prompt to run on the fetched content
}
```
**Output:**
```python theme={null}
{
"response": str, # AI model's response to the prompt
"url": str, # URL that was fetched
"final_url": str | None, # Final URL after redirects
"status_code": int | None # HTTP status code
}
```
### WebSearch
**Tool name:** `WebSearch`
**Input:**
```python theme={null}
{
"query": str, # The search query to use
"allowed_domains": list[str] | None, # Only include results from these domains
"blocked_domains": list[str] | None # Never include results from these domains
}
```
**Output:**
```python theme={null}
{
"results": [
{
"title": str,
"url": str,
"snippet": str,
"metadata": dict | None
}
],
"total_results": int,
"query": str
}
```
### TodoWrite
**Tool name:** `TodoWrite`
**Input:**
```python theme={null}
{
"todos": [
{
"content": str, # The task description
"status": "pending" | "in_progress" | "completed", # Task status
"activeForm": str # Active form of the description
}
]
}
```
**Output:**
```python theme={null}
{
"message": str, # Success message
"stats": {
"total": int,
"pending": int,
"in_progress": int,
"completed": int
}
}
```
### BashOutput
**Tool name:** `BashOutput`
**Input:**
```python theme={null}
{
"bash_id": str, # The ID of the background shell
"filter": str | None # Optional regex to filter output lines
}
```
**Output:**
```python theme={null}
{
"output": str, # New output since last check
"status": "running" | "completed" | "failed", # Current shell status
"exitCode": int | None # Exit code when completed
}
```
### KillBash
**Tool name:** `KillBash`
**Input:**
```python theme={null}
{
"shell_id": str # The ID of the background shell to kill
}
```
**Output:**
```python theme={null}
{
"message": str, # Success message
"shell_id": str # ID of the killed shell
}
```
### ExitPlanMode
**Tool name:** `ExitPlanMode`
**Input:**
```python theme={null}
{
"plan": str # The plan to run by the user for approval
}
```
**Output:**
```python theme={null}
{
"message": str, # Confirmation message
"approved": bool | None # Whether user approved the plan
}
```
### ListMcpResources
**Tool name:** `ListMcpResources`
**Input:**
```python theme={null}
{
"server": str | None # Optional server name to filter resources by
}
```
**Output:**
```python theme={null}
{
"resources": [
{
"uri": str,
"name": str,
"description": str | None,
"mimeType": str | None,
"server": str
}
],
"total": int
}
```
### ReadMcpResource
**Tool name:** `ReadMcpResource`
**Input:**
```python theme={null}
{
"server": str, # The MCP server name
"uri": str # The resource URI to read
}
```
**Output:**
```python theme={null}
{
"contents": [
{
"uri": str,
"mimeType": str | None,
"text": str | None,
"blob": str | None
}
],
"server": str
}
```
## Advanced Features with ClaudeSDKClient
### Building a Continuous Conversation Interface
```python theme={null}
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions, AssistantMessage, TextBlock
import asyncio
class ConversationSession:
"""Maintains a single conversation session with Claude."""
def __init__(self, options: ClaudeAgentOptions = None):
self.client = ClaudeSDKClient(options)
self.turn_count = 0
async def start(self):
await self.client.connect()
print("Starting conversation session. Claude will remember context.")
print("Commands: 'exit' to quit, 'interrupt' to stop current task, 'new' for new session")
while True:
user_input = input(f"\n[Turn {self.turn_count + 1}] You: ")
if user_input.lower() == 'exit':
break
elif user_input.lower() == 'interrupt':
await self.client.interrupt()
print("Task interrupted!")
continue
elif user_input.lower() == 'new':
# Disconnect and reconnect for a fresh session
await self.client.disconnect()
await self.client.connect()
self.turn_count = 0
print("Started new conversation session (previous context cleared)")
continue
# Send message - Claude remembers all previous messages in this session
await self.client.query(user_input)
self.turn_count += 1
# Process response
print(f"[Turn {self.turn_count}] Claude: ", end="")
async for message in self.client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(block.text, end="")
print() # New line after response
await self.client.disconnect()
print(f"Conversation ended after {self.turn_count} turns.")
async def main():
options = ClaudeAgentOptions(
allowed_tools=["Read", "Write", "Bash"],
permission_mode="acceptEdits"
)
session = ConversationSession(options)
await session.start()
# Example conversation:
# Turn 1 - You: "Create a file called hello.py"
# Turn 1 - Claude: "I'll create a hello.py file for you..."
# Turn 2 - You: "What's in that file?"
# Turn 2 - Claude: "The hello.py file I just created contains..." (remembers!)
# Turn 3 - You: "Add a main function to it"
# Turn 3 - Claude: "I'll add a main function to hello.py..." (knows which file!)
asyncio.run(main())
```
### Using Hooks for Behavior Modification
```python theme={null}
from claude_agent_sdk import (
ClaudeSDKClient,
ClaudeAgentOptions,
HookMatcher,
HookContext
)
import asyncio
from typing import Any
async def pre_tool_logger(
input_data: dict[str, Any],
tool_use_id: str | None,
context: HookContext
) -> dict[str, Any]:
"""Log all tool usage before execution."""
tool_name = input_data.get('tool_name', 'unknown')
print(f"[PRE-TOOL] About to use: {tool_name}")
# You can modify or block the tool execution here
if tool_name == "Bash" and "rm -rf" in str(input_data.get('tool_input', {})):
return {
'hookSpecificOutput': {
'hookEventName': 'PreToolUse',
'permissionDecision': 'deny',
'permissionDecisionReason': 'Dangerous command blocked'
}
}
return {}
async def post_tool_logger(
input_data: dict[str, Any],
tool_use_id: str | None,
context: HookContext
) -> dict[str, Any]:
"""Log results after tool execution."""
tool_name = input_data.get('tool_name', 'unknown')
print(f"[POST-TOOL] Completed: {tool_name}")
return {}
async def user_prompt_modifier(
input_data: dict[str, Any],
tool_use_id: str | None,
context: HookContext
) -> dict[str, Any]:
"""Add context to user prompts."""
original_prompt = input_data.get('prompt', '')
# Add timestamp to all prompts
from datetime import datetime
timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
return {
'hookSpecificOutput': {
'hookEventName': 'UserPromptSubmit',
'updatedPrompt': f"[{timestamp}] {original_prompt}"
}
}
async def main():
options = ClaudeAgentOptions(
hooks={
'PreToolUse': [
HookMatcher(hooks=[pre_tool_logger]),
HookMatcher(matcher='Bash', hooks=[pre_tool_logger])
],
'PostToolUse': [
HookMatcher(hooks=[post_tool_logger])
],
'UserPromptSubmit': [
HookMatcher(hooks=[user_prompt_modifier])
]
},
allowed_tools=["Read", "Write", "Bash"]
)
async with ClaudeSDKClient(options=options) as client:
await client.query("List files in current directory")
async for message in client.receive_response():
# Hooks will automatically log tool usage
pass
asyncio.run(main())
```
### Real-time Progress Monitoring
```python theme={null}
from claude_agent_sdk import (
ClaudeSDKClient,
ClaudeAgentOptions,
AssistantMessage,
ToolUseBlock,
ToolResultBlock,
TextBlock
)
import asyncio
async def monitor_progress():
options = ClaudeAgentOptions(
allowed_tools=["Write", "Bash"],
permission_mode="acceptEdits"
)
async with ClaudeSDKClient(options=options) as client:
await client.query(
"Create 5 Python files with different sorting algorithms"
)
# Monitor progress in real-time
files_created = []
async for message in client.receive_messages():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, ToolUseBlock):
if block.name == "Write":
file_path = block.input.get("file_path", "")
print(f"🔨 Creating: {file_path}")
elif isinstance(block, ToolResultBlock):
print(f"✅ Completed tool execution")
elif isinstance(block, TextBlock):
print(f"💭 Claude says: {block.text[:100]}...")
# Check if we've received the final result
if hasattr(message, 'subtype') and message.subtype in ['success', 'error']:
print(f"\n🎯 Task completed!")
break
asyncio.run(monitor_progress())
```
## Example Usage
### Basic file operations (using query)
```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions, AssistantMessage, ToolUseBlock
import asyncio
async def create_project():
options = ClaudeAgentOptions(
allowed_tools=["Read", "Write", "Bash"],
permission_mode='acceptEdits',
cwd="/home/user/project"
)
async for message in query(
prompt="Create a Python project structure with setup.py",
options=options
):
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, ToolUseBlock):
print(f"Using tool: {block.name}")
asyncio.run(create_project())
```
### Error handling
```python theme={null}
from claude_agent_sdk import (
query,
CLINotFoundError,
ProcessError,
CLIJSONDecodeError
)
try:
async for message in query(prompt="Hello"):
print(message)
except CLINotFoundError:
print("Please install Claude Code: npm install -g @anthropic-ai/claude-code")
except ProcessError as e:
print(f"Process failed with exit code: {e.exit_code}")
except CLIJSONDecodeError as e:
print(f"Failed to parse response: {e}")
```
### Streaming mode with client
```python theme={null}
from claude_agent_sdk import ClaudeSDKClient
import asyncio
async def interactive_session():
async with ClaudeSDKClient() as client:
# Send initial message
await client.query("What's the weather like?")
# Process responses
async for msg in client.receive_response():
print(msg)
# Send follow-up
await client.query("Tell me more about that")
# Process follow-up response
async for msg in client.receive_response():
print(msg)
asyncio.run(interactive_session())
```
### Using custom tools with ClaudeSDKClient
```python theme={null}
from claude_agent_sdk import (
ClaudeSDKClient,
ClaudeAgentOptions,
tool,
create_sdk_mcp_server,
AssistantMessage,
TextBlock
)
import asyncio
from typing import Any
# Define custom tools with @tool decorator
@tool("calculate", "Perform mathematical calculations", {"expression": str})
async def calculate(args: dict[str, Any]) -> dict[str, Any]:
try:
result = eval(args["expression"], {"__builtins__": {}})
return {
"content": [{
"type": "text",
"text": f"Result: {result}"
}]
}
except Exception as e:
return {
"content": [{
"type": "text",
"text": f"Error: {str(e)}"
}],
"is_error": True
}
@tool("get_time", "Get current time", {})
async def get_time(args: dict[str, Any]) -> dict[str, Any]:
from datetime import datetime
current_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
return {
"content": [{
"type": "text",
"text": f"Current time: {current_time}"
}]
}
async def main():
# Create SDK MCP server with custom tools
my_server = create_sdk_mcp_server(
name="utilities",
version="1.0.0",
tools=[calculate, get_time]
)
# Configure options with the server
options = ClaudeAgentOptions(
mcp_servers={"utils": my_server},
allowed_tools=[
"mcp__utils__calculate",
"mcp__utils__get_time"
]
)
# Use ClaudeSDKClient for interactive tool usage
async with ClaudeSDKClient(options=options) as client:
await client.query("What's 123 * 456?")
# Process calculation response
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Calculation: {block.text}")
# Follow up with time query
await client.query("What time is it now?")
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Time: {block.text}")
asyncio.run(main())
```
## See also
* [Python SDK guide](/en/api/agent-sdk/python) - Tutorial and examples
* [SDK overview](/en/api/agent-sdk/overview) - General SDK concepts
* [TypeScript SDK reference](/en/docs/claude-code/typescript-sdk-reference) - TypeScript SDK documentation
* [CLI reference](/en/docs/claude-code/cli-reference) - Command-line interface
* [Common workflows](/en/docs/claude-code/common-workflows) - Step-by-step guides