Claude Code SDK for Python

Python SDK for Claude Code. See the Claude Code SDK documentation for more information.

Installation

pip install claude-code-sdk

Prerequisites:

• Python 3.10+
• Node.js
• Claude Code: npm install -g @anthropic-ai/claude-code

Quick Start

import anyio
from claude_code_sdk import query

async def main():
    async for message in query(prompt="What is 2 + 2?"):
        print(message)

anyio.run(main)

Usage

Basic Query

from claude_code_sdk import query, ClaudeCodeOptions, AssistantMessage, TextBlock

# Simple query
async for message in query(prompt="Hello Claude"):
    if isinstance(message, AssistantMessage):
        for block in message.content:
            if isinstance(block, TextBlock):
                print(block.text)

# With options
options = ClaudeCodeOptions(
    system_prompt="You are a helpful assistant",
    max_turns=1
)

async for message in query(prompt="Tell me a joke", options=options):
    print(message)

Using Tools

options = ClaudeCodeOptions(
    allowed_tools=["Read", "Write", "Bash"],
    permission_mode='acceptEdits'  # auto-accept file edits
)

async for message in query(
    prompt="Create a hello.py file", 
    options=options
):
    # Process tool use and results
    pass

Working Directory

from pathlib import Path

options = ClaudeCodeOptions(
    cwd="/path/to/project"  # or Path("/path/to/project")
)

SDK MCP Servers (In-Process)

The SDK now supports in-process MCP servers that run directly within your Python application, eliminating the need for separate processes.

Creating a Simple Tool

from claude_code_sdk import tool, create_sdk_mcp_server

# Define a tool using the @tool decorator
@tool("greet", "Greet a user", {"name": str})
async def greet_user(args):
    return {
        "content": [
            {"type": "text", "text": f"Hello, {args['name']}!"}
        ]
    }

# Create an SDK MCP server
server = create_sdk_mcp_server(
    name="my-tools",
    version="1.0.0",
    tools=[greet_user]
)

# Use it with Claude
options = ClaudeCodeOptions(
    mcp_servers={"tools": server}
)

async for message in query(prompt="Greet Alice", options=options):
    print(message)

Benefits Over External MCP Servers

• No subprocess management - Runs in the same process as your application
• Better performance - No IPC overhead for tool calls
• Simpler deployment - Single Python process instead of multiple
• Easier debugging - All code runs in the same process
• Type safety - Direct Python function calls with type hints

Migration from External Servers

# BEFORE: External MCP server (separate process)
options = ClaudeCodeOptions(
    mcp_servers={
        "calculator": {
            "type": "stdio",
            "command": "python",
            "args": ["-m", "calculator_server"]
        }
    }
)

# AFTER: SDK MCP server (in-process)
from my_tools import add, subtract  # Your tool functions

calculator = create_sdk_mcp_server(
    name="calculator",
    tools=[add, subtract]
)

options = ClaudeCodeOptions(
    mcp_servers={"calculator": calculator}
)

Mixed Server Support

You can use both SDK and external MCP servers together:

options = ClaudeCodeOptions(
    mcp_servers={
        "internal": sdk_server,      # In-process SDK server
        "external": {                # External subprocess server
            "type": "stdio",
            "command": "external-server"
        }
    }
)

API Reference

query(prompt, options=None)

Main async function for querying Claude.

Parameters:

• prompt (str): The prompt to send to Claude
• options (ClaudeCodeOptions): Optional configuration

Returns: AsyncIterator[Message] - Stream of response messages

Types

See src/claude_code_sdk/types.py for complete type definitions:

• ClaudeCodeOptions - Configuration options
• AssistantMessage, UserMessage, SystemMessage, ResultMessage - Message types
• TextBlock, ToolUseBlock, ToolResultBlock - Content blocks

Error Handling

from claude_code_sdk import (
    ClaudeSDKError,      # Base error
    CLINotFoundError,    # Claude Code not installed
    CLIConnectionError,  # Connection issues
    ProcessError,        # Process failed
    CLIJSONDecodeError,  # JSON parsing issues
)

try:
    async for message in query(prompt="Hello"):
        pass
except CLINotFoundError:
    print("Please install 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}")

See src/claude_code_sdk/_errors.py for all error types.

Available Tools

See the Claude Code documentation for a complete list of available tools.

Examples

See examples/quick_start.py for a complete working example.

License

MIT