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https://github.com/Piebald-AI/claude-code-system-prompts.git
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351 lines
12 KiB
Markdown
351 lines
12 KiB
Markdown
<!--
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name: 'Data: Agent SDK reference — Python'
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description: Python Agent SDK reference including installation, quick start, custom tools via MCP, and hooks
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ccVersion: 2.1.78
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-->
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# Agent SDK — Python
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The Claude Agent SDK provides a higher-level interface for building AI agents with built-in tools, safety features, and agentic capabilities.
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## Installation
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```bash
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pip install claude-agent-sdk
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```
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---
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## Quick Start
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```python
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import anyio
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from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage
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async def main():
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async for message in query(
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prompt="Explain this codebase",
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options=ClaudeAgentOptions(allowed_tools=["Read", "Glob", "Grep"])
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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anyio.run(main)
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```
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---
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## Built-in Tools
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| Tool | Description |
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| --------- | ------------------------------------ |
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| Read | Read files in the workspace |
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| Write | Create new files |
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| Edit | Make precise edits to existing files |
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| Bash | Execute shell commands |
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| Glob | Find files by pattern |
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| Grep | Search files by content |
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| WebSearch | Search the web for information |
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| WebFetch | Fetch and analyze web pages |
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| AskUserQuestion | Ask user clarifying questions |
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| Agent | Spawn subagents |
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---
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## Primary Interfaces
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### `query()` — Simple One-Shot Usage
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The `query()` function is the simplest way to run an agent. It returns an async iterator of messages.
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage
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async for message in query(
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prompt="Explain this codebase",
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options=ClaudeAgentOptions(allowed_tools=["Read", "Glob", "Grep"])
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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```
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### `ClaudeSDKClient` — Full Control
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`ClaudeSDKClient` provides full control over the agent lifecycle. Use it when you need custom tools, hooks, streaming, or the ability to interrupt execution.
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```python
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import anyio
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from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions, AssistantMessage, TextBlock
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async def main():
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options = ClaudeAgentOptions(allowed_tools=["Read", "Glob", "Grep"])
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async with ClaudeSDKClient(options=options) as client:
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await client.query("Explain this codebase")
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async for message in client.receive_response():
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if isinstance(message, AssistantMessage):
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for block in message.content:
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if isinstance(block, TextBlock):
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print(block.text)
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anyio.run(main)
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```
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`ClaudeSDKClient` supports:
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- **Context manager** (`async with`) for automatic resource cleanup
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- **`client.query(prompt)`** to send a prompt to the agent
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- **`receive_response()`** for streaming messages until completion
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- **`interrupt()`** to stop agent execution mid-task
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- **Required for custom tools** (via SDK MCP servers)
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---
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## Permission System
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage
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async for message in query(
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prompt="Refactor the authentication module",
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options=ClaudeAgentOptions(
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allowed_tools=["Read", "Edit", "Write"],
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permission_mode="acceptEdits" # Auto-accept file edits
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)
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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```
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Permission modes:
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- `"default"`: Prompt for dangerous operations
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- `"plan"`: Planning only, no execution
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- `"acceptEdits"`: Auto-accept file edits
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- `"bypassPermissions"`: Skip all prompts (use with caution)
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---
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## MCP (Model Context Protocol) Support
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage
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async for message in query(
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prompt="Open example.com and describe what you see",
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options=ClaudeAgentOptions(
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mcp_servers={
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"playwright": {"command": "npx", "args": ["@playwright/mcp@latest"]}
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}
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)
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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```
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---
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## Hooks
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Customize agent behavior with hooks using callback functions:
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, HookMatcher, ResultMessage
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async def log_file_change(input_data, tool_use_id, context):
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file_path = input_data.get('tool_input', {}).get('file_path', 'unknown')
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print(f"Modified: {file_path}")
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return {}
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async for message in query(
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prompt="Refactor utils.py",
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options=ClaudeAgentOptions(
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permission_mode="acceptEdits",
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hooks={
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"PostToolUse": [HookMatcher(matcher="Edit|Write", hooks=[log_file_change])]
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}
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)
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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```
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Hook callback inputs for tool-lifecycle events (`PreToolUse`, `PostToolUse`, `PostToolUseFailure`) include `agent_id` and `agent_type` fields, allowing hooks to identify which agent (main or subagent) triggered the tool call.
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Available hook events: `PreToolUse`, `PostToolUse`, `PostToolUseFailure`, `UserPromptSubmit`, `Stop`, `SubagentStop`, `PreCompact`, `Notification`, `SubagentStart`, `PermissionRequest`
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---
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## Common Options
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`query()` takes a top-level `prompt` (string) and an `options` object (`ClaudeAgentOptions`):
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```python
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async for message in query(prompt="...", options=ClaudeAgentOptions(...)):
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```
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| Option | Type | Description |
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| ----------------------------------- | ------ | -------------------------------------------------------------------------- |
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| `cwd` | string | Working directory for file operations |
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| `allowed_tools` | list | Tools the agent can use (e.g., `["Read", "Edit", "Bash"]`) |
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| `tools` | list | Built-in tools to make available (restricts the default set) |
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| `disallowed_tools` | list | Tools to explicitly disallow |
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| `permission_mode` | string | How to handle permission prompts |
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| `mcp_servers` | dict | MCP servers to connect to |
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| `hooks` | dict | Hooks for customizing behavior |
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| `system_prompt` | string | Custom system prompt |
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| `max_turns` | int | Maximum agent turns before stopping |
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| `max_budget_usd` | float | Maximum budget in USD for the query |
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| `model` | string | Model ID (default: determined by CLI) |
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| `agents` | dict | Subagent definitions (`dict[str, AgentDefinition]`) |
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| `output_format` | dict | Structured output schema |
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| `thinking` | dict | Thinking/reasoning control |
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| `betas` | list | Beta features to enable (e.g., `["context-1m-2025-08-07"]`) |
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| `setting_sources` | list | Settings to load (e.g., `["project"]`). Default: none (no CLAUDE.md files) |
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| `env` | dict | Environment variables to set for the session |
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---
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## Message Types
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage, SystemMessage
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async for message in query(
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prompt="Find TODO comments",
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options=ClaudeAgentOptions(allowed_tools=["Read", "Glob", "Grep"])
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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print(f"Stop reason: {message.stop_reason}") # e.g., "end_turn", "max_turns"
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elif isinstance(message, SystemMessage) and message.subtype == "init":
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session_id = message.data.get("session_id") # Capture for resuming later
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```
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Typed task message subclasses are available for better type safety when handling subagent task events:
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- `TaskStartedMessage` — emitted when a subagent task is registered
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- `TaskProgressMessage` — real-time progress updates with cumulative usage metrics
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- `TaskNotificationMessage` — task completion notifications
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`RateLimitEvent` is emitted when the rate limit status transitions (e.g., from `allowed` to `allowed_warning` or `rejected`). Use it to warn users or back off gracefully:
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, RateLimitEvent
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async for message in query(prompt="...", options=ClaudeAgentOptions()):
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if isinstance(message, RateLimitEvent):
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print(f"Rate limit status: {message.rate_limit_info.status}")
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if message.rate_limit_info.resets_at:
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print(f"Resets at: {message.rate_limit_info.resets_at}")
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```
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---
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## Subagents
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, AgentDefinition, ResultMessage
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async for message in query(
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prompt="Use the code-reviewer agent to review this codebase",
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options=ClaudeAgentOptions(
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allowed_tools=["Read", "Glob", "Grep", "Agent"],
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agents={
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"code-reviewer": AgentDefinition(
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description="Expert code reviewer for quality and security reviews.",
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prompt="Analyze code quality and suggest improvements.",
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tools=["Read", "Glob", "Grep"]
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)
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}
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)
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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```
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---
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## Error Handling
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```python
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from claude_agent_sdk import query, ClaudeAgentOptions, CLINotFoundError, CLIConnectionError, ResultMessage
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try:
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async for message in query(
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prompt="...",
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options=ClaudeAgentOptions(allowed_tools=["Read"])
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):
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if isinstance(message, ResultMessage):
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print(message.result)
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except CLINotFoundError:
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print("Claude Code CLI not found. Install with: pip install claude-agent-sdk")
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except CLIConnectionError as e:
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print(f"Connection error: {e}")
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```
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---
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## Session History
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Retrieve past session data with top-level functions:
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```python
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from claude_agent_sdk import list_sessions, get_session_messages
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# List all past sessions (sync function — no await)
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sessions = list_sessions()
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for session in sessions:
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print(f"{session.session_id}: {session.cwd}")
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# Get messages from a specific session (sync function — no await)
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messages = get_session_messages(session_id="...")
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for msg in messages:
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print(msg)
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```
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### Session Mutations
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Rename or tag sessions (sync functions — no await):
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```python
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from claude_agent_sdk import rename_session, tag_session
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# Rename a session
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rename_session(session_id="...", title="My refactoring session")
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# Tag a session (tags are Unicode-sanitized automatically)
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tag_session(session_id="...", tag="experiment")
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# Clear a tag
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tag_session(session_id="...", tag=None)
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# Optionally scope to a specific project directory
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rename_session(session_id="...", title="New title", directory="/path/to/project")
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```
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---
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## MCP Server Management
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Manage MCP servers at runtime using `ClaudeSDKClient`:
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```python
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async with ClaudeSDKClient(options=options) as client:
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# Reconnect a disconnected MCP server
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await client.reconnect_mcp_server("my-server")
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# Toggle an MCP server on/off
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await client.toggle_mcp_server("my-server", enabled=False)
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# Get status of all MCP servers
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status = await client.get_mcp_status() # returns McpStatusResponse
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```
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---
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## Best Practices
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1. **Always specify allowed_tools** — Explicitly list which tools the agent can use
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2. **Set working directory** — Always specify `cwd` for file operations
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3. **Use appropriate permission modes** — Start with `"default"` and only escalate when needed
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4. **Handle all message types** — Check for `ResultMessage` to get agent output
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5. **Limit max_turns** — Prevent runaway agents with reasonable limits
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