v1.4.0

What's Changed

• Update URL validation to allow file and other nonstandard schemas by @hmwildermuth in #207
• Add client handling for sampling, list roots, ping by @jerome3o-anthropic in #218
• Updated typing on request context for the server to use server session by @jerome3o-anthropic in #217
• Fix #177: Returning multiple tool results by @dsp-ant in #222
• Use proper generic for Context by @Kludex in #245
• Drop AbstractAsyncContextManager for proper type hint to BaseSession by @Kludex in #257
• Add ServerSessionT type var to Context by @Kludex in #271
• Create Client websocket.py by @calclavia in #179
• Close unclosed resources in the whole project by @Kludex in #267
• Add support for Linux configuration path in get_claude_config_path by @emsi in #270
• Release on GitHub release by @Kludex in #276
• Changed default log level to error by @Michaelzag in #258
• refactor: reorganize message handling for better type safety and clarity by @dsp-ant in #239

New Contributors

• @hmwildermuth made their first contribution in #207
• @Kludex made their first contribution in #245
• @calclavia made their first contribution in #179
• @emsi made their first contribution in #270
• @Michaelzag made their first contribution in #258

Full Changelog: v1.3.0...v1.4.0

v1.3.0

Python SDK 1.3.0 - 2025-02-20

Breaking Changes

• Context API Changes: The Context logging methods (info, debug, warning, error) are now async and must be awaited. (#172)

New Features

Lifespan Support

Added comprehensive server lifecycle management through the lifespan API:

@dataclass
class AppContext:
    db: Database

@asynccontextmanager
async def app_lifespan(server: FastMCP) -> AsyncIterator[AppContext]:
    try:
        await db.connect()
        yield AppContext(db=db)
    finally:
        await db.disconnect()

mcp = FastMCP("My App", lifespan=app_lifespan)

@mcp.tool()
def query_db(ctx: Context) -> str:
    db = ctx.request_context.lifespan_context["db"]
    return db.query()

(#203)

Async Resources

Added support for async resource functions in FastMCP:

@mcp.resource("users://{user_id}")
async def get_user(user_id: str) -> str:
    async with client.session() as session:
        response = await session.get(f"/users/{user_id}")
        return await response.text()

(#157)

Concurrent Request Handling

Made message handling concurrent, allowing multiple requests to be processed simultaneously. (#206)

Request Cancellation

Added support for canceling in-flight requests and cleaning up resources. (#167)

Server Instructions

Added support for the instructions field in server initialization, allowing servers to provide usage guidance. (#150)

Bug Fixes

• Fixed progress reporting for first tool call by correcting progress_token handling (#176)
• Fixed server crash when using debug logging (#158)
• Fixed resource template handling in FastMCP server (#137)
• Fixed MIME type preservation in resource responses (#170)
• Fixed documentation for environment variables in CLI commands (#149)
• Fixed request ID preservation in JSON-RPC responses (#205)

Dependency Updates

• Relaxed version constraints for better compatibility:
  • pydantic: Changed from >=2.10.1,<3.0.0 to >=2.7.2,<3.0.0
  • pydantic-settings: Changed from >=2.6.1 to >=2.5.2
  • uvicorn: Changed from >=0.30 to >=0.23.1
    (#180)

Examples

• Added a simple chatbot example client to demonstrate SDK usage (#98)

Client Improvements

• Added client support for sampling, list roots, and ping requests (#218)
• Added flexible type system for tool result returns (#222)

Compatibility and Platform Support

• Updated URL validation to allow file and other nonstandard schemas (#68fcf92)
• Force stdin/stdout encoding to UTF-8 for cross-platform compatibility (#d92ee8f)

Internal Improvements

• Improved type annotations for better IDE support (#181)
• Added comprehensive tests for SSE transport (#151)
• Updated types to match 2024-11-05 MCP schema (#165)
• Refactored request and notification handling for better code organization (#166)

New Contributors

• @salman1993 made their first contribution in #150
• @micpst made their first contribution in #158
• @3choff made their first contribution in #98
• @cr7258 made their first contribution in #149
• @sheffler made their first contribution in #172
• @jeremydanielfox made their first contribution in #180
• @zzstoatzz made their first contribution in #181

Full Changelog: v1.2.1...v1.3.0

v1.3.0rc1

Python SDK 1.3.0 Release Candidate 1

Breaking Changes

• Context API Changes: The Context logging methods (info, debug, warning, error) are now async and must be awaited. (#172)
• Resource Response Format: Standardized resource response format to return both content and MIME type. Method read_resource() now returns a tuple of (content, mime_type) instead of just content. (#170)

New Features

Lifespan Support

Added comprehensive server lifecycle management through the lifespan API:

@dataclass
class AppContext:
    db: Database

@asynccontextmanager
async def app_lifespan(server: FastMCP) -> AsyncIterator[AppContext]:
    try:
        await db.connect()
        yield AppContext(db=db)
    finally:
        await db.disconnect()

mcp = FastMCP("My App", lifespan=app_lifespan)

@mcp.tool()
def query_db(ctx: Context) -> str:
    db = ctx.request_context.lifespan_context["db"]
    return db.query()

(#203)

Async Resources

Added support for async resource functions in FastMCP:

@mcp.resource("users://{user_id}")
async def get_user(user_id: str) -> str:
    async with client.session() as session:
        response = await session.get(f"/users/{user_id}")
        return await response.text()

(#157)

Concurrent Request Handling

Made message handling concurrent, allowing multiple requests to be processed simultaneously. (#206)

Request Cancellation

Added support for canceling in-flight requests and cleaning up resources. (#167)

Server Instructions

Added support for the instructions field in server initialization, allowing servers to provide usage guidance. (#150)

Bug Fixes

• Fixed progress reporting for first tool call by correcting progress_token handling (#176)
• Fixed server crash when using debug logging (#158)
• Fixed resource template handling in FastMCP server (#137)
• Fixed MIME type preservation in resource responses (#170)
• Fixed documentation for environment variables in CLI commands (#149)
• Fixed request ID preservation in JSON-RPC responses (#205)

Dependency Updates

• Relaxed version constraints for better compatibility:
  • pydantic: Changed from >=2.10.1,<3.0.0 to >=2.7.2,<3.0.0
  • pydantic-settings: Changed from >=2.6.1 to >=2.5.2
  • uvicorn: Changed from >=0.30 to >=0.23.1
    (#180)

Examples

• Added a simple chatbot example client to demonstrate SDK usage (#98)

Internal Improvements

• Improved type annotations for better IDE support (#181)
• Added comprehensive tests for SSE transport (#151)
• Updated types to match 2024-11-05 MCP schema (#165)
• Refactored request and notification handling for better code organization (#166)

v1.2.1

Release Notes

Features

• Added support for async resources
• Added example and test for parameter descriptions in FastMCP tools

Bug Fixes

• Fixed MCP install command with environment variables
• Fixed resource template handling in FastMCP server (#129)
• Fixed package in the generated MCP run config (#128)
• Fixed FastMCP logger debug output
• Fixed handling of strings containing numbers in FastMCP (@sd2k, #142)

v1.2.0

A big thank you to @jlowin for the creation of the fantastic FastMCP, which is now included into the MCP SDK.

Backwards Compatibility

This release is semver compatible. Existing code will continue to work, unless code relied on re-experts from mcp.server. Version 2.0 of the SDK will remove the use of mcp.server.Server in favour of mcp.server.lowlevel.Server. To stay compatible with upcoming major versions, please change from mcp.server import Server to from mcp.server.lowlevel import Server.

Major Features

FastMCP Integration

• Integrated FastMCP as the recommended high-level server framework
• Added new mcp.server.fastmcp module with simplified decorator-based API
• Introduced FastMCP class for easier server creation and management
• Added comprehensive documentation and examples for FastMCP usage

New CLI Package

• Added new CLI package for improved developer experience
• Introduced mcp dev command for local development and testing
• Added mcp install command for Claude Desktop integration
• Added mcp run command for direct server execution

Improvements

Documentation

• Completely revamped README with new structure and examples
• Added detailed sections on core concepts (Resources, Tools, Prompts)
• Updated documentation to recommend FastMCP as primary API
• Added sections on development workflow and deployment options
• Improved example server documentation

Developer Experience

• Added pre-commit hooks for code quality
• Updated to Pydantic 2.10.0 for improved type checking
• Added uvicorn as a dependency for better server capabilities

Bug Fixes

• Fixed encoding errors in STDIO client (@SecretiveShell)
• Fixed deprecation warnings in core components
• Fixed Pydantic field handling for meta fields
• Fixed type issues throughout the codebase
• Fixed example server READMEs
• Added constructor for McpError to allow setting fields (@allenporter)

Breaking Changes

• Deprecated direct usage of mcp.server in favor of mcp.server.fastmcp
• Updated import paths for FastMCP integration
• Changed recommended installation to include CLI features (pip install "mcp[cli]")

Contributors

Special thanks to all contributors who made this release possible, including:

• @jlowin (FastMCP)
• Oskar Raszkiewicz
• @allenporter
• @SecretiveShell
• @restlessronin

Full Changelog: v1.1.3...v1.2.0

v1.1.3

What's Changed

🐛 Bug Fixes

• Fixed encoding errors in STDIO client (@SecretiveShell)
• Fixed deprecation warnings
• Fixed pydantic Field usage with alias for _meta fields
• Added constructor for McpError to allow setting fields (@allenporter)

✨ Features

• Added version string parameter to Server constructor and initialization options (@restlessronin)

🙌 New Contributors

• @allenporter
• @SecretiveShell
• @restlessronin

Thank you for your contributions!

v1.2.0rc1

MCP Python SDK v1.2.0rc1 Release Notes

Major Features

FastMCP Integration

• Integrated FastMCP as the recommended high-level server framework
• Added new mcp.server.fastmcp module with simplified decorator-based API
• Introduced FastMCP class for easier server creation and management
• Added comprehensive documentation and examples for FastMCP usage

New CLI Package

• Added new CLI package for improved developer experience
• Introduced mcp dev command for local development and testing
• Added mcp install command for Claude Desktop integration
• Added mcp run command for direct server execution

Improvements

Documentation

• Completely revamped README with new structure and examples
• Added detailed sections on core concepts (Resources, Tools, Prompts)
• Updated documentation to recommend FastMCP as primary API
• Added sections on development workflow and deployment options
• Improved example server documentation

Developer Experience

• Added pre-commit hooks for code quality
• Updated to Pydantic 2.10.0 for improved type checking
• Added uvicorn as a dependency for better server capabilities

Bug Fixes

• Fixed deprecation warnings in core components
• Fixed Pydantic field handling for meta fields
• Fixed type issues throughout the codebase
• Fixed example server READMEs

Breaking Changes

• Deprecated direct usage of mcp.server in favor of mcp.server.fastmcp
• Updated import paths for FastMCP integration
• Changed recommended installation to include CLI features (pip install "mcp[cli]")

Contributors

Special thanks to all contributors who made this release possible, including:

• Jeremiah Lowin (FastMCP)
• Oskar Raszkiewicz

Full Changelog: v1.1.2...v1.2.0rc1

v1.1.2

Full Changelog: v1.1.1...v1.1.2

v1.1.1

Full Changelog: v1.1.0...v1.1.1

v1.1.0

What's Changed

• Fix first Python demo so it works without further modifications by @simonw in #66
• Fix experimental capabilities example by @jspahrsummers in #70
• Add handler for resource templates by @dsp-ant in #77
• Updated example in README.md for increased outreach by @miguelg719 in #82

New Contributors

• @simonw made their first contribution in #66
• @miguelg719 made their first contribution in #82

Full Changelog: v1.0.0...v1.1.0