PyMCP Kit

Python CI codecov PyPI - Version PyPI Downloads Docs License: MIT Python 3.10+

Documentation | Quick Start | Tasks | Security | Middleware

PyMCP Kit is a capability-first MCP server toolkit for FastAPI. It keeps the built-in transport surface small, supports Streamable HTTP and stdio, and ships app-scoped registries, roots, tasks, and optional auth hooks without pulling in a larger framework.

Quick Start

Install from PyPI:

pip install pymcp-kit

For local development from this repo:

pip install -e .

Register tools, prompts, and resources, then build an app:

from pymcp import (
    CapabilitySettings,
    ServerSettings,
    create_app,
    prompt_registry,
    resource_registry,
    tool_registry,
)


@tool_registry.register
def add(a: float, b: float) -> str:
    return str(a + b)


@prompt_registry.register(description="Create a release summary prompt.")
def summarize_release(topic: str) -> str:
    return f"Summarize the release impact for {topic}."


@resource_registry.register(
    uri="memo://release-plan",
    name="release_plan",
    description="Latest release checklist",
    mime_type="text/markdown",
)
def release_plan() -> str:
    return "# Release Plan\n- freeze API\n- tag build\n"


app = create_app(
    server_settings=ServerSettings(
        name="demo-server",
        version="0.1.0",
        capabilities=CapabilitySettings(
            advertise_empty_prompts=False,
            advertise_empty_resources=False,
        ),
    )
)

The HTTP transport is mounted at /mcp. For local-process integrations, use run_stdio_server(app).

Hosted documentation is built from docs/ with MkDocs Material and published to GitHub Pages.

Features

• Streamable HTTP transport for networked MCP servers
• Stdio transport for local-process MCP hosts
• Tool, prompt, and resource registries
• Roots, resource subscriptions, and app-scoped session lifecycle
• Task-aware tool execution with progress, cancellation, and result polling
• Optional authentication and authorization hooks
• Capability advertising through CapabilitySettings
• FastAPI middleware integration through MiddlewareConfig
• Small surface area focused on practical MCP server builds

Supported MCP Methods

• initialize, ping, notifications/initialized, and notifications/cancelled
• tools/list and tools/call
• prompts/list and prompts/get
• resources/list, resources/read, resources/subscribe, and resources/unsubscribe
• roots/list
• tasks/list, tasks/get, tasks/cancel, and tasks/result

Example Server

Run the bundled example server:

python example/run_server.py

That starts a FastAPI app on http://127.0.0.1:8088 with the MCP endpoint mounted at http://127.0.0.1:8088/mcp.

Stdio Transport

from pymcp import create_app, run_stdio_server


app = create_app()
run_stdio_server(app)

Middleware

Middleware stays separate from capability registration. Use MiddlewareConfig to control CORS, compression, logging, auth hooks, and custom ASGI middleware, then pass it into create_app(). See the hosted Middleware guide for examples.

Scope

• Prompts and resources are advertised only when registered by default
• Registries are copied into an app-scoped manager when create_app() runs
• Streamable HTTP and stdio are the only built-in transports
• Extra transports such as SSE and HTTP NDJSON are intentionally not shipped in pymcp-kit