531 lines
16 KiB
Markdown
531 lines
16 KiB
Markdown
---
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name: claude-api
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description: |
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Build with Claude Messages API using structured outputs (v0.69.0+, Nov 2025) for guaranteed JSON schema validation. Covers prompt caching (90% savings), streaming SSE, tool use, model deprecations (3.5/3.7 retired Oct 2025). Use when: building chatbots/agents with validated JSON responses, or troubleshooting rate_limit_error, structured output validation, prompt caching not activating, streaming SSE parsing.
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license: MIT
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metadata:
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version: 2.0.0
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last_verified: 2025-11-22
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sdk_version: 0.70.1
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token_savings: ~48%
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errors_prevented: 12
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breaking_changes: Oct 2025 - Claude 3.5/3.7 models retired, Nov 2025 - Structured outputs beta
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keywords:
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- claude api
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- anthropic api
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- messages api
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- "@anthropic-ai/sdk"
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- structured outputs
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- output_format
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- strict tool use
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- json schema validation
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- claude streaming
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- prompt caching
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- cache_control
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- tool use
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- vision
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- extended thinking
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- claude sonnet 4.5
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- claude haiku 4.5
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- claude opus 4
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- function calling
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- SSE
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- rate limits
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- 429 errors
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- agent skills api
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- context management
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- clear thinking
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- streaming sse parsing
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- prompt caching not working
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- structured output validation
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- model deprecated
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- model retired
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---
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# Claude API - Structured Outputs & Error Prevention Guide
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**Package**: @anthropic-ai/sdk@0.70.1 (Nov 20, 2025)
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**Breaking Changes**: Oct 2025 - Claude 3.5/3.7 models retired, Nov 2025 - Structured outputs beta
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**Last Updated**: 2025-11-22
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---
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## What's New in v0.69.0+ (Nov 2025)
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**Major Features:**
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### 1. Structured Outputs (v0.69.0, Nov 14, 2025) - CRITICAL ⭐
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**Guaranteed JSON schema conformance** - Claude's responses strictly follow your JSON schema with two modes:
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**JSON Outputs (`output_format`)** - For data extraction and formatting:
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```typescript
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import Anthropic from '@anthropic-ai/sdk';
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const anthropic = new Anthropic({
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apiKey: process.env.ANTHROPIC_API_KEY,
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});
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const message = await anthropic.messages.create({
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model: 'claude-sonnet-4-5-20250929',
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max_tokens: 1024,
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messages: [{ role: 'user', content: 'Extract contact info: John Doe, john@example.com, 555-1234' }],
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betas: ['structured-outputs-2025-11-13'],
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output_format: {
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type: 'json_schema',
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json_schema: {
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name: 'Contact',
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strict: true,
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schema: {
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type: 'object',
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properties: {
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name: { type: 'string' },
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email: { type: 'string' },
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phone: { type: 'string' }
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},
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required: ['name', 'email', 'phone'],
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additionalProperties: false
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}
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}
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}
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});
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// Guaranteed valid JSON matching schema
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const contact = JSON.parse(message.content[0].text);
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console.log(contact.name); // "John Doe"
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```
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**Strict Tool Use (`strict: true`)** - For validated function parameters:
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```typescript
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const message = await anthropic.messages.create({
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model: 'claude-sonnet-4-5-20250929',
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max_tokens: 1024,
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messages: [{ role: 'user', content: 'Get weather for San Francisco' }],
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betas: ['structured-outputs-2025-11-13'],
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tools: [{
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name: 'get_weather',
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description: 'Get current weather',
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input_schema: {
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type: 'object',
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properties: {
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location: { type: 'string' },
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unit: { type: 'string', enum: ['celsius', 'fahrenheit'] }
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},
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required: ['location'],
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additionalProperties: false
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},
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strict: true // ← Guarantees schema compliance
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}]
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});
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```
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**Requirements:**
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- **Beta header**: `structured-outputs-2025-11-13` (via `betas` array)
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- **Models**: Claude Sonnet 4.5, Claude Opus 4.1 only
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- **SDK**: v0.69.0+ required
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**Limitations:**
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- ❌ No recursive schemas
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- ❌ No numerical constraints (`minimum`, `maximum`)
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- ❌ Limited regex support (no backreferences/lookahead)
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- ❌ Incompatible with citations and message prefilling
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- ⚠️ Grammar compilation adds latency on first request (cached 24hrs)
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**When to Use:**
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- Data extraction from unstructured text
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- API response formatting
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- Agentic workflows requiring validated tool inputs
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- Eliminating JSON parse errors
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### 2. Model Changes (Oct 2025) - BREAKING
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**Retired (return errors):**
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- ❌ Claude 3.5 Sonnet (all versions)
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- ❌ Claude 3.7 Sonnet - DEPRECATED (Oct 28, 2025)
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**Active Models (Nov 2025):**
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| Model | ID | Context | Best For | Cost (per MTok) |
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|-------|-----|---------|----------|-----------------|
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| **Claude Sonnet 4.5** | claude-sonnet-4-5-20250929 | 200k | Balanced performance | $3/$15 (in/out) |
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| **Claude Opus 4** | claude-opus-4-20250514 | 200k | Highest capability | $15/$75 |
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| **Claude Haiku 4.5** | claude-3-5-haiku-20241022 | 200k | Near-frontier, fast | $1/$5 |
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### 3. Context Management (Oct 28, 2025)
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**Clear Thinking Blocks** - Automatic thinking block cleanup:
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```typescript
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const message = await anthropic.messages.create({
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model: 'claude-sonnet-4-5-20250929',
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max_tokens: 4096,
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messages: [{ role: 'user', content: 'Solve complex problem' }],
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betas: ['clear_thinking_20251015']
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});
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// Thinking blocks automatically managed
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```
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### 4. Agent Skills API (Oct 16, 2025)
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Pre-built skills for Office files (PowerPoint, Excel, Word, PDF):
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```typescript
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const message = await anthropic.messages.create({
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model: 'claude-sonnet-4-5-20250929',
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max_tokens: 1024,
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messages: [{ role: 'user', content: 'Analyze this spreadsheet' }],
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betas: ['skills-2025-10-02'],
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// Requires code execution tool enabled
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});
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```
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📚 **Docs**: https://platform.claude.com/docs/en/build-with-claude/structured-outputs
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---
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## Streaming Responses (SSE)
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**CRITICAL Error Pattern** - Errors occur AFTER initial 200 response:
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```typescript
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const stream = anthropic.messages.stream({
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model: 'claude-sonnet-4-5-20250929',
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max_tokens: 1024,
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messages: [{ role: 'user', content: 'Hello' }],
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});
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stream
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.on('error', (error) => {
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// Error can occur AFTER stream starts
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console.error('Stream error:', error);
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// Implement fallback or retry logic
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})
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.on('abort', (error) => {
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console.warn('Stream aborted:', error);
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});
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```
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**Why this matters**: Unlike regular HTTP errors, SSE errors happen mid-stream after 200 OK, requiring error event listeners
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---
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## Prompt Caching (⭐ 90% Cost Savings)
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**CRITICAL Rule** - `cache_control` MUST be on LAST block:
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```typescript
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const message = await anthropic.messages.create({
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model: 'claude-sonnet-4-5-20250929',
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max_tokens: 1024,
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system: [
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{
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type: 'text',
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text: 'System instructions...',
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},
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{
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type: 'text',
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text: LARGE_CODEBASE, // 50k tokens
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cache_control: { type: 'ephemeral' }, // ← MUST be on LAST block
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},
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],
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messages: [{ role: 'user', content: 'Explain auth module' }],
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});
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// Monitor cache usage
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console.log('Cache reads:', message.usage.cache_read_input_tokens);
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console.log('Cache writes:', message.usage.cache_creation_input_tokens);
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```
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**Minimum requirements:**
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- Claude Sonnet 4.5: 1,024 tokens minimum
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- Claude Haiku 4.5: 2,048 tokens minimum
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- 5-minute TTL (refreshes on each use)
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- Cache shared only with IDENTICAL content
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---
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## Tool Use (Function Calling)
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**CRITICAL Patterns:**
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**Strict Tool Use** (with structured outputs):
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```typescript
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const message = await anthropic.messages.create({
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model: 'claude-sonnet-4-5-20250929',
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max_tokens: 1024,
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betas: ['structured-outputs-2025-11-13'],
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tools: [{
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name: 'get_weather',
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description: 'Get weather data',
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input_schema: {
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type: 'object',
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properties: {
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location: { type: 'string' },
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unit: { type: 'string', enum: ['celsius', 'fahrenheit'] }
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},
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required: ['location'],
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additionalProperties: false
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},
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strict: true // ← Guarantees schema compliance
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}],
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messages: [{ role: 'user', content: 'Weather in NYC?' }]
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});
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```
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**Tool Result Pattern** - `tool_use_id` MUST match:
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```typescript
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const toolResults = [];
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for (const block of response.content) {
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if (block.type === 'tool_use') {
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const result = await executeToolFunction(block.name, block.input);
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toolResults.push({
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type: 'tool_result',
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tool_use_id: block.id, // ← MUST match tool_use block id
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content: JSON.stringify(result),
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});
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}
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}
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messages.push({
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role: 'user',
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content: toolResults,
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});
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```
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**Error Handling** - Handle tool execution failures:
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```typescript
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try {
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const result = await executeToolFunction(block.name, block.input);
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toolResults.push({
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type: 'tool_result',
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tool_use_id: block.id,
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content: JSON.stringify(result),
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});
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} catch (error) {
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// Return error to Claude for handling
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toolResults.push({
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type: 'tool_result',
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tool_use_id: block.id,
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is_error: true,
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content: `Tool execution failed: ${error.message}`,
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});
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}
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```
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---
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## Vision (Image Understanding)
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**CRITICAL Rules:**
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- **Formats**: JPEG, PNG, WebP, GIF (non-animated)
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- **Max size**: 5MB per image
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- **Base64 overhead**: ~33% size increase
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- **Context impact**: Images count toward token limit
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- **Caching**: Consider for repeated image analysis
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**Format validation** - Check before encoding:
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```typescript
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const validFormats = ['image/jpeg', 'image/png', 'image/webp', 'image/gif'];
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if (!validFormats.includes(mimeType)) {
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throw new Error(`Unsupported format: ${mimeType}`);
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}
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```
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---
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## Extended Thinking Mode
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**⚠️ Model Compatibility:**
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- ❌ Claude 3.7 Sonnet - DEPRECATED (Oct 28, 2025)
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- ❌ Claude 3.5 Sonnet - RETIRED (not supported)
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- ✅ Claude Sonnet 4.5 - Extended thinking supported
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- ✅ Claude Opus 4 - Extended thinking supported
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**CRITICAL:**
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- Thinking blocks are NOT cacheable
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- Requires higher `max_tokens` (thinking consumes tokens)
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- Check model before expecting thinking blocks
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---
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## Rate Limits
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**CRITICAL Pattern** - Respect `retry-after` header with exponential backoff:
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```typescript
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async function makeRequestWithRetry(
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requestFn: () => Promise<any>,
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maxRetries = 3,
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baseDelay = 1000
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): Promise<any> {
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for (let attempt = 0; attempt < maxRetries; attempt++) {
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try {
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return await requestFn();
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} catch (error) {
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if (error.status === 429) {
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// CRITICAL: Use retry-after header if present
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const retryAfter = error.response?.headers?.['retry-after'];
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const delay = retryAfter
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? parseInt(retryAfter) * 1000
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: baseDelay * Math.pow(2, attempt);
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console.warn(`Rate limited. Retrying in ${delay}ms...`);
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await new Promise(resolve => setTimeout(resolve, delay));
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} else {
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throw error;
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}
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}
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}
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throw new Error('Max retries exceeded');
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}
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```
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**Rate limit headers:**
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- `anthropic-ratelimit-requests-limit` - Total RPM allowed
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- `anthropic-ratelimit-requests-remaining` - Remaining requests
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- `anthropic-ratelimit-requests-reset` - Reset timestamp
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---
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## Error Handling
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**Common Error Codes:**
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| Status | Error Type | Cause | Solution |
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|--------|-----------|-------|----------|
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| 400 | invalid_request_error | Bad parameters | Validate request body |
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| 401 | authentication_error | Invalid API key | Check env variable |
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| 403 | permission_error | No access to feature | Check account tier |
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| 404 | not_found_error | Invalid endpoint | Check API version |
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| 429 | rate_limit_error | Too many requests | Implement retry logic |
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| 500 | api_error | Internal error | Retry with backoff |
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| 529 | overloaded_error | System overloaded | Retry later |
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**CRITICAL:**
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- Streaming errors occur AFTER initial 200 response
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- Always implement error event listeners for streams
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- Respect `retry-after` header on 429 errors
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- Have fallback strategies for critical operations
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---
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## Known Issues Prevention
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This skill prevents **12** documented issues:
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### Issue #1: Rate Limit 429 Errors Without Backoff
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**Error**: `429 Too Many Requests: Number of request tokens has exceeded your per-minute rate limit`
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**Source**: https://docs.claude.com/en/api/errors
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**Why It Happens**: Exceeding RPM, TPM, or daily token limits
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**Prevention**: Implement exponential backoff with `retry-after` header respect
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### Issue #2: Streaming SSE Parsing Errors
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**Error**: Incomplete chunks, malformed SSE events
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**Source**: Common SDK issue (GitHub #323)
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**Why It Happens**: Network interruptions, improper event parsing
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**Prevention**: Use SDK stream helpers, implement error event listeners
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### Issue #3: Prompt Caching Not Activating
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**Error**: High costs despite cache_control blocks
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**Source**: https://platform.claude.com/docs/en/build-with-claude/prompt-caching
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**Why It Happens**: `cache_control` placed incorrectly (must be at END)
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**Prevention**: Always place `cache_control` on LAST block of cacheable content
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### Issue #4: Tool Use Response Format Errors
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**Error**: `invalid_request_error: tools[0].input_schema is invalid`
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**Source**: API validation errors
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**Why It Happens**: Invalid JSON Schema, missing required fields
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**Prevention**: Validate schemas with JSON Schema validator, test thoroughly
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### Issue #5: Vision Image Format Issues
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**Error**: `invalid_request_error: image source must be base64 or url`
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**Source**: API documentation
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**Why It Happens**: Incorrect encoding, unsupported formats
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**Prevention**: Validate format (JPEG/PNG/WebP/GIF), proper base64 encoding
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### Issue #6: Token Counting Mismatches for Billing
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**Error**: Unexpected high costs, context window exceeded
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**Source**: Token counting differences
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**Why It Happens**: Not accounting for special tokens, formatting
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**Prevention**: Use official token counter, monitor usage headers
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### Issue #7: System Prompt Ordering Issues
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**Error**: System prompt ignored or overridden
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**Source**: API behavior
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**Why It Happens**: System prompt placed after messages array
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**Prevention**: ALWAYS place system prompt before messages
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### Issue #8: Context Window Exceeded (200k)
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**Error**: `invalid_request_error: messages: too many tokens`
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**Source**: Model limits
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**Why It Happens**: Long conversations without pruning
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**Prevention**: Implement message history pruning, use caching
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### Issue #9: Extended Thinking on Wrong Model
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**Error**: No thinking blocks in response
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**Source**: Model capabilities
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**Why It Happens**: Using retired/deprecated models (3.5/3.7 Sonnet)
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**Prevention**: Only use extended thinking with Claude Sonnet 4.5 or Claude Opus 4
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### Issue #10: API Key Exposure in Client Code
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**Error**: CORS errors, security vulnerability
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**Source**: Security best practices
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**Why It Happens**: Making API calls from browser
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**Prevention**: Server-side only, use environment variables
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### Issue #11: Rate Limit Tier Confusion
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**Error**: Lower limits than expected
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**Source**: Account tier system
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**Why It Happens**: Not understanding tier progression
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**Prevention**: Check Console for current tier, auto-scales with usage
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### Issue #12: Message Batches Beta Headers Missing
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**Error**: `invalid_request_error: unknown parameter: batches`
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**Source**: Beta API requirements
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**Why It Happens**: Missing `anthropic-beta` header
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**Prevention**: Include `anthropic-beta: message-batches-2024-09-24` header
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---
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## Official Documentation
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- **Claude API**: https://platform.claude.com/docs/en/api
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- **Messages API**: https://platform.claude.com/docs/en/api/messages
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- **Structured Outputs**: https://platform.claude.com/docs/en/build-with-claude/structured-outputs
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- **Prompt Caching**: https://platform.claude.com/docs/en/build-with-claude/prompt-caching
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- **Tool Use**: https://platform.claude.com/docs/en/build-with-claude/tool-use
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- **Vision**: https://platform.claude.com/docs/en/build-with-claude/vision
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- **Rate Limits**: https://platform.claude.com/docs/en/api/rate-limits
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- **Errors**: https://platform.claude.com/docs/en/api/errors
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- **TypeScript SDK**: https://github.com/anthropics/anthropic-sdk-typescript
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- **Context7 Library ID**: /anthropics/anthropic-sdk-typescript
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---
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## Package Versions
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**Latest**: @anthropic-ai/sdk@0.70.1 (Nov 20, 2025)
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```json
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{
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"dependencies": {
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"@anthropic-ai/sdk": "^0.70.1"
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},
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"devDependencies": {
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"@types/node": "^20.0.0",
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"typescript": "^5.3.0",
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"zod": "^3.23.0"
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}
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}
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```
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---
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**Token Efficiency**:
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- **Without skill**: ~8,000 tokens (basic setup, streaming, caching, tools, vision, errors)
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- **With skill**: ~4,200 tokens (knowledge gaps + error prevention + critical patterns)
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- **Savings**: ~48% (~3,800 tokens)
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**Errors prevented**: 12 documented issues with exact solutions
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**Key value**: Structured outputs (v0.69.0+), model deprecations (Oct 2025), prompt caching edge cases, streaming error patterns, rate limit retry logic
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---
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**Last verified**: 2025-11-22 | **Skill version**: 2.0.0 | **Changes**: Added structured outputs (v0.69.0), updated model table (retired 3.5/3.7), context management, agent skills API. Removed basic tutorials (~380 lines). Focused on knowledge gaps + error prevention + advanced patterns.
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