v1.8.1

What's Changed

• Fix streamable http sampling by @ihrpr in #693

Full Changelog: v1.8.0...v1.8.1

v1.8.0

Streamable HTTP release

This is the first release supporting the new Streamable HTTP transport from protocol version 2025-03-26, which supersedes the SSE transport from protocol version 2024-11-05. 🎉
Please report any issues at https://github.com/modelcontextprotocol/python-sdk/issues

Other Changes

• Handle SSE Disconnects Properly by @akash329d in #612
• Add mount_path support for proper SSE endpoint routing with multiple FastMCP servers by @tim-watcha in #540
• docs: fix broken link to OAuthServerProvider in Authentication section of README by @samad-yar-khan in #651
• Fix the issue of get Authorization header fails during bearer auth by @yabea in #637
• Auth SSE simple example by @ihrpr in #610
• Fix: Use absolute path to uv executable in Claude Desktop config by @arcAman07 in #440
• Introduce a function to create a standard AsyncClient with options by @ihrpr in #655

New Contributors

• @akash329d made their first contribution in #612
• @tim-watcha made their first contribution in #540
• @samad-yar-khan made their first contribution in #651
• @yabea made their first contribution in #637
• @arcAman07 made their first contribution in #440

Full Changelog: v1.7.0...v1.8.0

v1.7.1

Full Changelog: v1.7.0...v1.7.1

v1.7.0

OAuth Support for servers

• Add support for serverside oauth by @praboud-ant in #255

Tool Annotations

• Add ToolAnnotations support in FastMCP and lowlevel servers by @bhosmer-ant in #482

Other changes

• Docs: Change README to correct pip installation command for MCP CLI support by @codingjenny in #394

• Fix python -m command error by @xuzexin-hz in #387

• Docs : Enhance README to suggest commands for creating a new UV project before adding mcp dependency. by @anupsajjan in #408

• Fix lifespan_context access example in README by @SigureMo in #437

• Match ruff version on CI and local by @Kludex in #471

• Fix @mcp.tool() Failing to Detect Context Argument When Type Variables Are Used in Context by @jkawamoto in #358

• Support custom client info throughout client APIs by @jerome3o-anthropic in #474

• Fix tests for Pydantic 2.11 by @medaminezghal in #465

• Move uvicorn import to usage by @danlapid in #502

• Python lint: Ruff rules for comprehensions and performance by @cclauss in #512

• Format files with ruff by @ihrpr in #562

• replace inefficient use of to_jsonable_python by @samuelcolvin in #545

• add a timeout arguments on per-request basis (as per MCP specifications) by @grll in #601

• add pytest-pretty dev dependency by @samuelcolvin in #546

• Properly clean up response streams in BaseSession by @bhosmer-ant in #515

New Contributors

• @codingjenny made their first contribution in #394
• @xuzexin-hz made their first contribution in #387
• @anupsajjan made their first contribution in #408
• @SigureMo made their first contribution in #437
• @jkawamoto made their first contribution in #358
• @medaminezghal made their first contribution in #465
• @danlapid made their first contribution in #502
• @cclauss made their first contribution in #512
• @grll made their first contribution in #601
• @bhosmer-ant made their first contribution in #482
• @praboud-ant made their first contribution in #255

Full Changelog: v1.6.0...v1.7.0

v1.6.0

What's Changed

• Fix #201: Move incoming message stream from BaseSession to ServerSession by @dsp-ant in #325
• default log level info by @barnuri in #366
• ci: test multiple python versions by @Kludex in #345
• Add mkdocs by @Kludex in #367
• Fix #355: Fix type error with lifespan context by @dsp-ant in #368
• refactor: Make types.py strictly typechecked. by @dsp-ant in #336
• Fix typo in starlette import in README by @conorbranagan in #374
• Fixes to stdio_client to support Windows more robustly by @saqadri in #372
• Fix/base64 handling (Issue #342) by @evalstate in #343

New Contributors

• @barnuri made their first contribution in #366
• @conorbranagan made their first contribution in #374
• @saqadri made their first contribution in #372
• @evalstate made their first contribution in #343

Full Changelog: v1.5.0...v1.6.0

v1.5.0

What's Changed

• Strict types on the client side by @Kludex in #285
• lint docs examples by @samuelcolvin in #286
• Avoid double JSON encoding/decoding by @Kludex in #287
• Improve readability of CLI help option by @Kludex in #295
• Option to mount SSE server to existing ASGI server by @comfuture in #312
• Add callback for logging message notification to client by @ihrpr in #314
• add cwd to StdioServerParameters by @samuelcolvin in #292
• docs(examples): fixing the prompts example by @Niraj-Fonseka in #318
• Add strict mode to pyright by @Kludex in #315
• Enhancement: make stderr of server subprocess configurable by @sheffler in #191
• Update init.py by @arthrod in #335
• Update types.py by @NinoRisteski in #243
• enable custom path of sse server by @elsejj in #246
• Use default environment even when env is provided by @maxguru in #327

New Contributors

• @samuelcolvin made their first contribution in #286
• @comfuture made their first contribution in #312
• @ihrpr made their first contribution in #314
• @Niraj-Fonseka made their first contribution in #318
• @arthrod made their first contribution in #335
• @NinoRisteski made their first contribution in #243
• @elsejj made their first contribution in #246
• @maxguru made their first contribution in #327

Full Changelog: v1.4.1...v1.4.2

v1.4.1

What's Changed

• Update README to clarify installing mcp to project vs running mcp by @john0312 in #277
• Revert "refactor: reorganize message handling for better type safety and clarity" by @Kludex in #282

New Contributors

• @john0312 made their first contribution in #277

Full Changelog: v1.4.0...v1.4.1

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)