python-sdk/docs/migration.md

Migration Guide: v1 to v2

This guide covers the breaking changes introduced in v2 of the MCP Python SDK and how to update your code.

Overview

Version 2 of the MCP Python SDK introduces several breaking changes to improve the API, align with the MCP specification, and provide better type safety.

Breaking Changes

streamablehttp_client removed

The deprecated streamablehttp_client function has been removed. Use streamable_http_client instead.

Before (v1):

from mcp.client.streamable_http import streamablehttp_client

async with streamablehttp_client(
    url="http://localhost:8000/mcp",
    headers={"Authorization": "Bearer token"},
    timeout=30,
    sse_read_timeout=300,
    auth=my_auth,
) as (read_stream, write_stream, get_session_id):
    ...

After (v2):

import httpx
from mcp.client.streamable_http import streamable_http_client

# Configure headers, timeout, and auth on the httpx.AsyncClient
http_client = httpx.AsyncClient(
    headers={"Authorization": "Bearer token"},
    timeout=httpx.Timeout(30, read=300),
    auth=my_auth,
)

async with http_client:
    async with streamable_http_client(
        url="http://localhost:8000/mcp",
        http_client=http_client,
    ) as (read_stream, write_stream, get_session_id):
        ...

StreamableHTTPTransport parameters removed

The headers, timeout, sse_read_timeout, and auth parameters have been removed from StreamableHTTPTransport. Configure these on the httpx.AsyncClient instead (see example above).

Content type alias removed

The deprecated Content type alias has been removed. Use ContentBlock directly instead.

Before (v1):

from mcp.types import Content

After (v2):

from mcp.types import ContentBlock

args parameter removed from ClientSessionGroup.call_tool()

The deprecated args parameter has been removed from ClientSessionGroup.call_tool(). Use arguments instead.

Before (v1):

result = await session_group.call_tool("my_tool", args={"key": "value"})

After (v2):

result = await session_group.call_tool("my_tool", arguments={"key": "value"})

Deprecations

New Features

Need Help?

If you encounter issues during migration:

1. Check the API Reference for updated method signatures
2. Review the examples for updated usage patterns
3. Open an issue on GitHub if you find a bug or need further assistance