Claude API

---
name: claude-api
description: |
  Trigger when code imports anthropic, @anthropic-ai/sdk, or claude_agent_sdk,
  or when the user asks to use the Claude API, Anthropic SDKs, or Agent SDK.
  Do NOT trigger for other AI SDKs (openai, etc.).
allowed-tools:
  - Bash(command *)
  - Read
  - Write
  - Edit
  - Glob
  - Grep
---

# Claude API

Build applications using the Claude API and Anthropic SDKs including tool use,
streaming, extended thinking, and agentic patterns.

## Prerequisites

- Anthropic API key set as `ANTHROPIC_API_KEY` env var
- SDK installed: `npm install @anthropic-ai/sdk` or `pip install anthropic`

## Key Patterns

### Basic message
```typescript
import Anthropic from "@anthropic-ai/sdk";
const client = new Anthropic();

const message = await client.messages.create({
  model: "claude-sonnet-4-20250514",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello" }],
});
```

### Streaming
```typescript
const stream = client.messages.stream({
  model: "claude-sonnet-4-20250514",
  max_tokens: 1024,
  messages: [{ role: "user", content: prompt }],
});
for await (const event of stream) {
  if (event.type === "content_block_delta" && event.delta.type === "text_delta") {
    process.stdout.write(event.delta.text);
  }
}
```

### Tool use
```typescript
const response = await client.messages.create({
  model: "claude-sonnet-4-20250514",
  max_tokens: 1024,
  tools: [{
    name: "get_weather",
    description: "Get weather for a city",
    input_schema: {
      type: "object",
      properties: { city: { type: "string" } },
      required: ["city"],
    },
  }],
  messages: [{ role: "user", content: "Weather in Tokyo?" }],
});
```

## Steps

1. Check which SDK version is installed
2. Use the correct model identifier (claude-sonnet-4-20250514, etc.)
3. Always handle rate limits with exponential backoff
4. For streaming apps, use `.stream()` not `.create()`
5. For tool use, validate tool inputs before executing