Name | mcp JSON |
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1.5.0
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Summary | Model Context Protocol SDK |
upload_time | 2025-03-21 12:51:04 |
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docs_url | None |
author | Anthropic, PBC. |
requires_python | >=3.10 |
license | MIT |
keywords |
automation
git
llm
mcp
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# MCP Python SDK
<div align="center">
<strong>Python implementation of the Model Context Protocol (MCP)</strong>
[![PyPI][pypi-badge]][pypi-url]
[![MIT licensed][mit-badge]][mit-url]
[![Python Version][python-badge]][python-url]
[![Documentation][docs-badge]][docs-url]
[![Specification][spec-badge]][spec-url]
[![GitHub Discussions][discussions-badge]][discussions-url]
</div>
<!-- omit in toc -->
## Table of Contents
- [MCP Python SDK](#mcp-python-sdk)
- [Overview](#overview)
- [Installation](#installation)
- [Adding MCP to your python project](#adding-mcp-to-your-python-project)
- [Running the standalone MCP development tools](#running-the-standalone-mcp-development-tools)
- [Quickstart](#quickstart)
- [What is MCP?](#what-is-mcp)
- [Core Concepts](#core-concepts)
- [Server](#server)
- [Resources](#resources)
- [Tools](#tools)
- [Prompts](#prompts)
- [Images](#images)
- [Context](#context)
- [Running Your Server](#running-your-server)
- [Development Mode](#development-mode)
- [Claude Desktop Integration](#claude-desktop-integration)
- [Direct Execution](#direct-execution)
- [Mounting to an Existing ASGI Server](#mounting-to-an-existing-asgi-server)
- [Examples](#examples)
- [Echo Server](#echo-server)
- [SQLite Explorer](#sqlite-explorer)
- [Advanced Usage](#advanced-usage)
- [Low-Level Server](#low-level-server)
- [Writing MCP Clients](#writing-mcp-clients)
- [MCP Primitives](#mcp-primitives)
- [Server Capabilities](#server-capabilities)
- [Documentation](#documentation)
- [Contributing](#contributing)
- [License](#license)
[pypi-badge]: https://img.shields.io/pypi/v/mcp.svg
[pypi-url]: https://pypi.org/project/mcp/
[mit-badge]: https://img.shields.io/pypi/l/mcp.svg
[mit-url]: https://github.com/modelcontextprotocol/python-sdk/blob/main/LICENSE
[python-badge]: https://img.shields.io/pypi/pyversions/mcp.svg
[python-url]: https://www.python.org/downloads/
[docs-badge]: https://img.shields.io/badge/docs-modelcontextprotocol.io-blue.svg
[docs-url]: https://modelcontextprotocol.io
[spec-badge]: https://img.shields.io/badge/spec-spec.modelcontextprotocol.io-blue.svg
[spec-url]: https://spec.modelcontextprotocol.io
[discussions-badge]: https://img.shields.io/github/discussions/modelcontextprotocol/python-sdk
[discussions-url]: https://github.com/modelcontextprotocol/python-sdk/discussions
## Overview
The Model Context Protocol allows applications to provide context for LLMs in a standardized way, separating the concerns of providing context from the actual LLM interaction. This Python SDK implements the full MCP specification, making it easy to:
- Build MCP clients that can connect to any MCP server
- Create MCP servers that expose resources, prompts and tools
- Use standard transports like stdio and SSE
- Handle all MCP protocol messages and lifecycle events
## Installation
### Adding MCP to your python project
We recommend using [uv](https://docs.astral.sh/uv/) to manage your Python projects. In a uv managed python project, add mcp to dependencies by:
```bash
uv add "mcp[cli]"
```
Alternatively, for projects using pip for dependencies:
```bash
pip install mcp
```
### Running the standalone MCP development tools
To run the mcp command with uv:
```bash
uv run mcp
```
## Quickstart
Let's create a simple MCP server that exposes a calculator tool and some data:
```python
# server.py
from mcp.server.fastmcp import FastMCP
# Create an MCP server
mcp = FastMCP("Demo")
# Add an addition tool
@mcp.tool()
def add(a: int, b: int) -> int:
"""Add two numbers"""
return a + b
# Add a dynamic greeting resource
@mcp.resource("greeting://{name}")
def get_greeting(name: str) -> str:
"""Get a personalized greeting"""
return f"Hello, {name}!"
```
You can install this server in [Claude Desktop](https://claude.ai/download) and interact with it right away by running:
```bash
mcp install server.py
```
Alternatively, you can test it with the MCP Inspector:
```bash
mcp dev server.py
```
## What is MCP?
The [Model Context Protocol (MCP)](https://modelcontextprotocol.io) lets you build servers that expose data and functionality to LLM applications in a secure, standardized way. Think of it like a web API, but specifically designed for LLM interactions. MCP servers can:
- Expose data through **Resources** (think of these sort of like GET endpoints; they are used to load information into the LLM's context)
- Provide functionality through **Tools** (sort of like POST endpoints; they are used to execute code or otherwise produce a side effect)
- Define interaction patterns through **Prompts** (reusable templates for LLM interactions)
- And more!
## Core Concepts
### Server
The FastMCP server is your core interface to the MCP protocol. It handles connection management, protocol compliance, and message routing:
```python
# Add lifespan support for startup/shutdown with strong typing
from contextlib import asynccontextmanager
from collections.abc import AsyncIterator
from dataclasses import dataclass
from fake_database import Database # Replace with your actual DB type
from mcp.server.fastmcp import Context, FastMCP
# Create a named server
mcp = FastMCP("My App")
# Specify dependencies for deployment and development
mcp = FastMCP("My App", dependencies=["pandas", "numpy"])
@dataclass
class AppContext:
db: Database
@asynccontextmanager
async def app_lifespan(server: FastMCP) -> AsyncIterator[AppContext]:
"""Manage application lifecycle with type-safe context"""
# Initialize on startup
db = await Database.connect()
try:
yield AppContext(db=db)
finally:
# Cleanup on shutdown
await db.disconnect()
# Pass lifespan to server
mcp = FastMCP("My App", lifespan=app_lifespan)
# Access type-safe lifespan context in tools
@mcp.tool()
def query_db(ctx: Context) -> str:
"""Tool that uses initialized resources"""
db = ctx.request_context.lifespan_context["db"]
return db.query()
```
### Resources
Resources are how you expose data to LLMs. They're similar to GET endpoints in a REST API - they provide data but shouldn't perform significant computation or have side effects:
```python
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("My App")
@mcp.resource("config://app")
def get_config() -> str:
"""Static configuration data"""
return "App configuration here"
@mcp.resource("users://{user_id}/profile")
def get_user_profile(user_id: str) -> str:
"""Dynamic user data"""
return f"Profile data for user {user_id}"
```
### Tools
Tools let LLMs take actions through your server. Unlike resources, tools are expected to perform computation and have side effects:
```python
import httpx
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("My App")
@mcp.tool()
def calculate_bmi(weight_kg: float, height_m: float) -> float:
"""Calculate BMI given weight in kg and height in meters"""
return weight_kg / (height_m**2)
@mcp.tool()
async def fetch_weather(city: str) -> str:
"""Fetch current weather for a city"""
async with httpx.AsyncClient() as client:
response = await client.get(f"https://api.weather.com/{city}")
return response.text
```
### Prompts
Prompts are reusable templates that help LLMs interact with your server effectively:
```python
from mcp.server.fastmcp import FastMCP
from mcp.server.fastmcp.prompts import base
mcp = FastMCP("My App")
@mcp.prompt()
def review_code(code: str) -> str:
return f"Please review this code:\n\n{code}"
@mcp.prompt()
def debug_error(error: str) -> list[base.Message]:
return [
base.UserMessage("I'm seeing this error:"),
base.UserMessage(error),
base.AssistantMessage("I'll help debug that. What have you tried so far?"),
]
```
### Images
FastMCP provides an `Image` class that automatically handles image data:
```python
from mcp.server.fastmcp import FastMCP, Image
from PIL import Image as PILImage
mcp = FastMCP("My App")
@mcp.tool()
def create_thumbnail(image_path: str) -> Image:
"""Create a thumbnail from an image"""
img = PILImage.open(image_path)
img.thumbnail((100, 100))
return Image(data=img.tobytes(), format="png")
```
### Context
The Context object gives your tools and resources access to MCP capabilities:
```python
from mcp.server.fastmcp import FastMCP, Context
mcp = FastMCP("My App")
@mcp.tool()
async def long_task(files: list[str], ctx: Context) -> str:
"""Process multiple files with progress tracking"""
for i, file in enumerate(files):
ctx.info(f"Processing {file}")
await ctx.report_progress(i, len(files))
data, mime_type = await ctx.read_resource(f"file://{file}")
return "Processing complete"
```
## Running Your Server
### Development Mode
The fastest way to test and debug your server is with the MCP Inspector:
```bash
mcp dev server.py
# Add dependencies
mcp dev server.py --with pandas --with numpy
# Mount local code
mcp dev server.py --with-editable .
```
### Claude Desktop Integration
Once your server is ready, install it in Claude Desktop:
```bash
mcp install server.py
# Custom name
mcp install server.py --name "My Analytics Server"
# Environment variables
mcp install server.py -v API_KEY=abc123 -v DB_URL=postgres://...
mcp install server.py -f .env
```
### Direct Execution
For advanced scenarios like custom deployments:
```python
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("My App")
if __name__ == "__main__":
mcp.run()
```
Run it with:
```bash
python server.py
# or
mcp run server.py
```
### Mounting to an Existing ASGI Server
You can mount the SSE server to an existing ASGI server using the `sse_app` method. This allows you to integrate the SSE server with other ASGI applications.
```python
from starlette.applications import Starlette
from starlette.routes import Mount, Host
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("My App")
# Mount the SSE server to the existing ASGI server
app = Starlette(
routes=[
Mount('/', app=mcp.sse_app()),
]
)
# or dynamically mount as host
app.router.routes.append(Host('mcp.acme.corp', app=mcp.sse_app()))
```
For more information on mounting applications in Starlette, see the [Starlette documentation](https://www.starlette.io/routing/#submounting-routes).
## Examples
### Echo Server
A simple server demonstrating resources, tools, and prompts:
```python
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("Echo")
@mcp.resource("echo://{message}")
def echo_resource(message: str) -> str:
"""Echo a message as a resource"""
return f"Resource echo: {message}"
@mcp.tool()
def echo_tool(message: str) -> str:
"""Echo a message as a tool"""
return f"Tool echo: {message}"
@mcp.prompt()
def echo_prompt(message: str) -> str:
"""Create an echo prompt"""
return f"Please process this message: {message}"
```
### SQLite Explorer
A more complex example showing database integration:
```python
import sqlite3
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("SQLite Explorer")
@mcp.resource("schema://main")
def get_schema() -> str:
"""Provide the database schema as a resource"""
conn = sqlite3.connect("database.db")
schema = conn.execute("SELECT sql FROM sqlite_master WHERE type='table'").fetchall()
return "\n".join(sql[0] for sql in schema if sql[0])
@mcp.tool()
def query_data(sql: str) -> str:
"""Execute SQL queries safely"""
conn = sqlite3.connect("database.db")
try:
result = conn.execute(sql).fetchall()
return "\n".join(str(row) for row in result)
except Exception as e:
return f"Error: {str(e)}"
```
## Advanced Usage
### Low-Level Server
For more control, you can use the low-level server implementation directly. This gives you full access to the protocol and allows you to customize every aspect of your server, including lifecycle management through the lifespan API:
```python
from contextlib import asynccontextmanager
from collections.abc import AsyncIterator
from fake_database import Database # Replace with your actual DB type
from mcp.server import Server
@asynccontextmanager
async def server_lifespan(server: Server) -> AsyncIterator[dict]:
"""Manage server startup and shutdown lifecycle."""
# Initialize resources on startup
db = await Database.connect()
try:
yield {"db": db}
finally:
# Clean up on shutdown
await db.disconnect()
# Pass lifespan to server
server = Server("example-server", lifespan=server_lifespan)
# Access lifespan context in handlers
@server.call_tool()
async def query_db(name: str, arguments: dict) -> list:
ctx = server.request_context
db = ctx.lifespan_context["db"]
return await db.query(arguments["query"])
```
The lifespan API provides:
- A way to initialize resources when the server starts and clean them up when it stops
- Access to initialized resources through the request context in handlers
- Type-safe context passing between lifespan and request handlers
```python
import mcp.server.stdio
import mcp.types as types
from mcp.server.lowlevel import NotificationOptions, Server
from mcp.server.models import InitializationOptions
# Create a server instance
server = Server("example-server")
@server.list_prompts()
async def handle_list_prompts() -> list[types.Prompt]:
return [
types.Prompt(
name="example-prompt",
description="An example prompt template",
arguments=[
types.PromptArgument(
name="arg1", description="Example argument", required=True
)
],
)
]
@server.get_prompt()
async def handle_get_prompt(
name: str, arguments: dict[str, str] | None
) -> types.GetPromptResult:
if name != "example-prompt":
raise ValueError(f"Unknown prompt: {name}")
return types.GetPromptResult(
description="Example prompt",
messages=[
types.PromptMessage(
role="user",
content=types.TextContent(type="text", text="Example prompt text"),
)
],
)
async def run():
async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
await server.run(
read_stream,
write_stream,
InitializationOptions(
server_name="example",
server_version="0.1.0",
capabilities=server.get_capabilities(
notification_options=NotificationOptions(),
experimental_capabilities={},
),
),
)
if __name__ == "__main__":
import asyncio
asyncio.run(run())
```
### Writing MCP Clients
The SDK provides a high-level client interface for connecting to MCP servers:
```python
from mcp import ClientSession, StdioServerParameters, types
from mcp.client.stdio import stdio_client
# Create server parameters for stdio connection
server_params = StdioServerParameters(
command="python", # Executable
args=["example_server.py"], # Optional command line arguments
env=None, # Optional environment variables
)
# Optional: create a sampling callback
async def handle_sampling_message(
message: types.CreateMessageRequestParams,
) -> types.CreateMessageResult:
return types.CreateMessageResult(
role="assistant",
content=types.TextContent(
type="text",
text="Hello, world! from model",
),
model="gpt-3.5-turbo",
stopReason="endTurn",
)
async def run():
async with stdio_client(server_params) as (read, write):
async with ClientSession(
read, write, sampling_callback=handle_sampling_message
) as session:
# Initialize the connection
await session.initialize()
# List available prompts
prompts = await session.list_prompts()
# Get a prompt
prompt = await session.get_prompt(
"example-prompt", arguments={"arg1": "value"}
)
# List available resources
resources = await session.list_resources()
# List available tools
tools = await session.list_tools()
# Read a resource
content, mime_type = await session.read_resource("file://some/path")
# Call a tool
result = await session.call_tool("tool-name", arguments={"arg1": "value"})
if __name__ == "__main__":
import asyncio
asyncio.run(run())
```
### MCP Primitives
The MCP protocol defines three core primitives that servers can implement:
| Primitive | Control | Description | Example Use |
|-----------|-----------------------|-----------------------------------------------------|------------------------------|
| Prompts | User-controlled | Interactive templates invoked by user choice | Slash commands, menu options |
| Resources | Application-controlled| Contextual data managed by the client application | File contents, API responses |
| Tools | Model-controlled | Functions exposed to the LLM to take actions | API calls, data updates |
### Server Capabilities
MCP servers declare capabilities during initialization:
| Capability | Feature Flag | Description |
|-------------|------------------------------|------------------------------------|
| `prompts` | `listChanged` | Prompt template management |
| `resources` | `subscribe`<br/>`listChanged`| Resource exposure and updates |
| `tools` | `listChanged` | Tool discovery and execution |
| `logging` | - | Server logging configuration |
| `completion`| - | Argument completion suggestions |
## Documentation
- [Model Context Protocol documentation](https://modelcontextprotocol.io)
- [Model Context Protocol specification](https://spec.modelcontextprotocol.io)
- [Officially supported servers](https://github.com/modelcontextprotocol/servers)
## Contributing
We are passionate about supporting contributors of all levels of experience and would love to see you get involved in the project. See the [contributing guide](CONTRIBUTING.md) to get started.
## License
This project is licensed under the MIT License - see the LICENSE file for details.
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"description": "# MCP Python SDK\n\n<div align=\"center\">\n\n<strong>Python implementation of the Model Context Protocol (MCP)</strong>\n\n[![PyPI][pypi-badge]][pypi-url]\n[![MIT licensed][mit-badge]][mit-url]\n[![Python Version][python-badge]][python-url]\n[![Documentation][docs-badge]][docs-url]\n[![Specification][spec-badge]][spec-url]\n[![GitHub Discussions][discussions-badge]][discussions-url]\n\n</div>\n\n<!-- omit in toc -->\n## Table of Contents\n\n- [MCP Python SDK](#mcp-python-sdk)\n - [Overview](#overview)\n - [Installation](#installation)\n - [Adding MCP to your python project](#adding-mcp-to-your-python-project)\n - [Running the standalone MCP development tools](#running-the-standalone-mcp-development-tools)\n - [Quickstart](#quickstart)\n - [What is MCP?](#what-is-mcp)\n - [Core Concepts](#core-concepts)\n - [Server](#server)\n - [Resources](#resources)\n - [Tools](#tools)\n - [Prompts](#prompts)\n - [Images](#images)\n - [Context](#context)\n - [Running Your Server](#running-your-server)\n - [Development Mode](#development-mode)\n - [Claude Desktop Integration](#claude-desktop-integration)\n - [Direct Execution](#direct-execution)\n - [Mounting to an Existing ASGI Server](#mounting-to-an-existing-asgi-server)\n - [Examples](#examples)\n - [Echo Server](#echo-server)\n - [SQLite Explorer](#sqlite-explorer)\n - [Advanced Usage](#advanced-usage)\n - [Low-Level Server](#low-level-server)\n - [Writing MCP Clients](#writing-mcp-clients)\n - [MCP Primitives](#mcp-primitives)\n - [Server Capabilities](#server-capabilities)\n - [Documentation](#documentation)\n - [Contributing](#contributing)\n - [License](#license)\n\n[pypi-badge]: https://img.shields.io/pypi/v/mcp.svg\n[pypi-url]: https://pypi.org/project/mcp/\n[mit-badge]: https://img.shields.io/pypi/l/mcp.svg\n[mit-url]: https://github.com/modelcontextprotocol/python-sdk/blob/main/LICENSE\n[python-badge]: https://img.shields.io/pypi/pyversions/mcp.svg\n[python-url]: https://www.python.org/downloads/\n[docs-badge]: https://img.shields.io/badge/docs-modelcontextprotocol.io-blue.svg\n[docs-url]: https://modelcontextprotocol.io\n[spec-badge]: https://img.shields.io/badge/spec-spec.modelcontextprotocol.io-blue.svg\n[spec-url]: https://spec.modelcontextprotocol.io\n[discussions-badge]: https://img.shields.io/github/discussions/modelcontextprotocol/python-sdk\n[discussions-url]: https://github.com/modelcontextprotocol/python-sdk/discussions\n\n## Overview\n\nThe Model Context Protocol allows applications to provide context for LLMs in a standardized way, separating the concerns of providing context from the actual LLM interaction. This Python SDK implements the full MCP specification, making it easy to:\n\n- Build MCP clients that can connect to any MCP server\n- Create MCP servers that expose resources, prompts and tools\n- Use standard transports like stdio and SSE\n- Handle all MCP protocol messages and lifecycle events\n\n## Installation\n\n### Adding MCP to your python project\n\nWe recommend using [uv](https://docs.astral.sh/uv/) to manage your Python projects. In a uv managed python project, add mcp to dependencies by:\n\n```bash\nuv add \"mcp[cli]\"\n```\n\nAlternatively, for projects using pip for dependencies:\n```bash\npip install mcp\n```\n\n### Running the standalone MCP development tools\n\nTo run the mcp command with uv:\n\n```bash\nuv run mcp\n```\n\n## Quickstart\n\nLet's create a simple MCP server that exposes a calculator tool and some data:\n\n```python\n# server.py\nfrom mcp.server.fastmcp import FastMCP\n\n# Create an MCP server\nmcp = FastMCP(\"Demo\")\n\n\n# Add an addition tool\n@mcp.tool()\ndef add(a: int, b: int) -> int:\n \"\"\"Add two numbers\"\"\"\n return a + b\n\n\n# Add a dynamic greeting resource\n@mcp.resource(\"greeting://{name}\")\ndef get_greeting(name: str) -> str:\n \"\"\"Get a personalized greeting\"\"\"\n return f\"Hello, {name}!\"\n```\n\nYou can install this server in [Claude Desktop](https://claude.ai/download) and interact with it right away by running:\n```bash\nmcp install server.py\n```\n\nAlternatively, you can test it with the MCP Inspector:\n```bash\nmcp dev server.py\n```\n\n## What is MCP?\n\nThe [Model Context Protocol (MCP)](https://modelcontextprotocol.io) lets you build servers that expose data and functionality to LLM applications in a secure, standardized way. Think of it like a web API, but specifically designed for LLM interactions. MCP servers can:\n\n- Expose data through **Resources** (think of these sort of like GET endpoints; they are used to load information into the LLM's context)\n- Provide functionality through **Tools** (sort of like POST endpoints; they are used to execute code or otherwise produce a side effect)\n- Define interaction patterns through **Prompts** (reusable templates for LLM interactions)\n- And more!\n\n## Core Concepts\n\n### Server\n\nThe FastMCP server is your core interface to the MCP protocol. It handles connection management, protocol compliance, and message routing:\n\n```python\n# Add lifespan support for startup/shutdown with strong typing\nfrom contextlib import asynccontextmanager\nfrom collections.abc import AsyncIterator\nfrom dataclasses import dataclass\n\nfrom fake_database import Database # Replace with your actual DB type\n\nfrom mcp.server.fastmcp import Context, FastMCP\n\n# Create a named server\nmcp = FastMCP(\"My App\")\n\n# Specify dependencies for deployment and development\nmcp = FastMCP(\"My App\", dependencies=[\"pandas\", \"numpy\"])\n\n\n@dataclass\nclass AppContext:\n db: Database\n\n\n@asynccontextmanager\nasync def app_lifespan(server: FastMCP) -> AsyncIterator[AppContext]:\n \"\"\"Manage application lifecycle with type-safe context\"\"\"\n # Initialize on startup\n db = await Database.connect()\n try:\n yield AppContext(db=db)\n finally:\n # Cleanup on shutdown\n await db.disconnect()\n\n\n# Pass lifespan to server\nmcp = FastMCP(\"My App\", lifespan=app_lifespan)\n\n\n# Access type-safe lifespan context in tools\n@mcp.tool()\ndef query_db(ctx: Context) -> str:\n \"\"\"Tool that uses initialized resources\"\"\"\n db = ctx.request_context.lifespan_context[\"db\"]\n return db.query()\n```\n\n### Resources\n\nResources are how you expose data to LLMs. They're similar to GET endpoints in a REST API - they provide data but shouldn't perform significant computation or have side effects:\n\n```python\nfrom mcp.server.fastmcp import FastMCP\n\nmcp = FastMCP(\"My App\")\n\n\n@mcp.resource(\"config://app\")\ndef get_config() -> str:\n \"\"\"Static configuration data\"\"\"\n return \"App configuration here\"\n\n\n@mcp.resource(\"users://{user_id}/profile\")\ndef get_user_profile(user_id: str) -> str:\n \"\"\"Dynamic user data\"\"\"\n return f\"Profile data for user {user_id}\"\n```\n\n### Tools\n\nTools let LLMs take actions through your server. Unlike resources, tools are expected to perform computation and have side effects:\n\n```python\nimport httpx\nfrom mcp.server.fastmcp import FastMCP\n\nmcp = FastMCP(\"My App\")\n\n\n@mcp.tool()\ndef calculate_bmi(weight_kg: float, height_m: float) -> float:\n \"\"\"Calculate BMI given weight in kg and height in meters\"\"\"\n return weight_kg / (height_m**2)\n\n\n@mcp.tool()\nasync def fetch_weather(city: str) -> str:\n \"\"\"Fetch current weather for a city\"\"\"\n async with httpx.AsyncClient() as client:\n response = await client.get(f\"https://api.weather.com/{city}\")\n return response.text\n```\n\n### Prompts\n\nPrompts are reusable templates that help LLMs interact with your server effectively:\n\n```python\nfrom mcp.server.fastmcp import FastMCP\nfrom mcp.server.fastmcp.prompts import base\n\nmcp = FastMCP(\"My App\")\n\n\n@mcp.prompt()\ndef review_code(code: str) -> str:\n return f\"Please review this code:\\n\\n{code}\"\n\n\n@mcp.prompt()\ndef debug_error(error: str) -> list[base.Message]:\n return [\n base.UserMessage(\"I'm seeing this error:\"),\n base.UserMessage(error),\n base.AssistantMessage(\"I'll help debug that. What have you tried so far?\"),\n ]\n```\n\n### Images\n\nFastMCP provides an `Image` class that automatically handles image data:\n\n```python\nfrom mcp.server.fastmcp import FastMCP, Image\nfrom PIL import Image as PILImage\n\nmcp = FastMCP(\"My App\")\n\n\n@mcp.tool()\ndef create_thumbnail(image_path: str) -> Image:\n \"\"\"Create a thumbnail from an image\"\"\"\n img = PILImage.open(image_path)\n img.thumbnail((100, 100))\n return Image(data=img.tobytes(), format=\"png\")\n```\n\n### Context\n\nThe Context object gives your tools and resources access to MCP capabilities:\n\n```python\nfrom mcp.server.fastmcp import FastMCP, Context\n\nmcp = FastMCP(\"My App\")\n\n\n@mcp.tool()\nasync def long_task(files: list[str], ctx: Context) -> str:\n \"\"\"Process multiple files with progress tracking\"\"\"\n for i, file in enumerate(files):\n ctx.info(f\"Processing {file}\")\n await ctx.report_progress(i, len(files))\n data, mime_type = await ctx.read_resource(f\"file://{file}\")\n return \"Processing complete\"\n```\n\n## Running Your Server\n\n### Development Mode\n\nThe fastest way to test and debug your server is with the MCP Inspector:\n\n```bash\nmcp dev server.py\n\n# Add dependencies\nmcp dev server.py --with pandas --with numpy\n\n# Mount local code\nmcp dev server.py --with-editable .\n```\n\n### Claude Desktop Integration\n\nOnce your server is ready, install it in Claude Desktop:\n\n```bash\nmcp install server.py\n\n# Custom name\nmcp install server.py --name \"My Analytics Server\"\n\n# Environment variables\nmcp install server.py -v API_KEY=abc123 -v DB_URL=postgres://...\nmcp install server.py -f .env\n```\n\n### Direct Execution\n\nFor advanced scenarios like custom deployments:\n\n```python\nfrom mcp.server.fastmcp import FastMCP\n\nmcp = FastMCP(\"My App\")\n\nif __name__ == \"__main__\":\n mcp.run()\n```\n\nRun it with:\n```bash\npython server.py\n# or\nmcp run server.py\n```\n\n### Mounting to an Existing ASGI Server\n\nYou can mount the SSE server to an existing ASGI server using the `sse_app` method. This allows you to integrate the SSE server with other ASGI applications.\n\n```python\nfrom starlette.applications import Starlette\nfrom starlette.routes import Mount, Host\nfrom mcp.server.fastmcp import FastMCP\n\n\nmcp = FastMCP(\"My App\")\n\n# Mount the SSE server to the existing ASGI server\napp = Starlette(\n routes=[\n Mount('/', app=mcp.sse_app()),\n ]\n)\n\n# or dynamically mount as host\napp.router.routes.append(Host('mcp.acme.corp', app=mcp.sse_app()))\n```\n\nFor more information on mounting applications in Starlette, see the [Starlette documentation](https://www.starlette.io/routing/#submounting-routes).\n\n## Examples\n\n### Echo Server\n\nA simple server demonstrating resources, tools, and prompts:\n\n```python\nfrom mcp.server.fastmcp import FastMCP\n\nmcp = FastMCP(\"Echo\")\n\n\n@mcp.resource(\"echo://{message}\")\ndef echo_resource(message: str) -> str:\n \"\"\"Echo a message as a resource\"\"\"\n return f\"Resource echo: {message}\"\n\n\n@mcp.tool()\ndef echo_tool(message: str) -> str:\n \"\"\"Echo a message as a tool\"\"\"\n return f\"Tool echo: {message}\"\n\n\n@mcp.prompt()\ndef echo_prompt(message: str) -> str:\n \"\"\"Create an echo prompt\"\"\"\n return f\"Please process this message: {message}\"\n```\n\n### SQLite Explorer\n\nA more complex example showing database integration:\n\n```python\nimport sqlite3\n\nfrom mcp.server.fastmcp import FastMCP\n\nmcp = FastMCP(\"SQLite Explorer\")\n\n\n@mcp.resource(\"schema://main\")\ndef get_schema() -> str:\n \"\"\"Provide the database schema as a resource\"\"\"\n conn = sqlite3.connect(\"database.db\")\n schema = conn.execute(\"SELECT sql FROM sqlite_master WHERE type='table'\").fetchall()\n return \"\\n\".join(sql[0] for sql in schema if sql[0])\n\n\n@mcp.tool()\ndef query_data(sql: str) -> str:\n \"\"\"Execute SQL queries safely\"\"\"\n conn = sqlite3.connect(\"database.db\")\n try:\n result = conn.execute(sql).fetchall()\n return \"\\n\".join(str(row) for row in result)\n except Exception as e:\n return f\"Error: {str(e)}\"\n```\n\n## Advanced Usage\n\n### Low-Level Server\n\nFor more control, you can use the low-level server implementation directly. This gives you full access to the protocol and allows you to customize every aspect of your server, including lifecycle management through the lifespan API:\n\n```python\nfrom contextlib import asynccontextmanager\nfrom collections.abc import AsyncIterator\n\nfrom fake_database import Database # Replace with your actual DB type\n\nfrom mcp.server import Server\n\n\n@asynccontextmanager\nasync def server_lifespan(server: Server) -> AsyncIterator[dict]:\n \"\"\"Manage server startup and shutdown lifecycle.\"\"\"\n # Initialize resources on startup\n db = await Database.connect()\n try:\n yield {\"db\": db}\n finally:\n # Clean up on shutdown\n await db.disconnect()\n\n\n# Pass lifespan to server\nserver = Server(\"example-server\", lifespan=server_lifespan)\n\n\n# Access lifespan context in handlers\n@server.call_tool()\nasync def query_db(name: str, arguments: dict) -> list:\n ctx = server.request_context\n db = ctx.lifespan_context[\"db\"]\n return await db.query(arguments[\"query\"])\n```\n\nThe lifespan API provides:\n- A way to initialize resources when the server starts and clean them up when it stops\n- Access to initialized resources through the request context in handlers\n- Type-safe context passing between lifespan and request handlers\n\n```python\nimport mcp.server.stdio\nimport mcp.types as types\nfrom mcp.server.lowlevel import NotificationOptions, Server\nfrom mcp.server.models import InitializationOptions\n\n# Create a server instance\nserver = Server(\"example-server\")\n\n\n@server.list_prompts()\nasync def handle_list_prompts() -> list[types.Prompt]:\n return [\n types.Prompt(\n name=\"example-prompt\",\n description=\"An example prompt template\",\n arguments=[\n types.PromptArgument(\n name=\"arg1\", description=\"Example argument\", required=True\n )\n ],\n )\n ]\n\n\n@server.get_prompt()\nasync def handle_get_prompt(\n name: str, arguments: dict[str, str] | None\n) -> types.GetPromptResult:\n if name != \"example-prompt\":\n raise ValueError(f\"Unknown prompt: {name}\")\n\n return types.GetPromptResult(\n description=\"Example prompt\",\n messages=[\n types.PromptMessage(\n role=\"user\",\n content=types.TextContent(type=\"text\", text=\"Example prompt text\"),\n )\n ],\n )\n\n\nasync def run():\n async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):\n await server.run(\n read_stream,\n write_stream,\n InitializationOptions(\n server_name=\"example\",\n server_version=\"0.1.0\",\n capabilities=server.get_capabilities(\n notification_options=NotificationOptions(),\n experimental_capabilities={},\n ),\n ),\n )\n\n\nif __name__ == \"__main__\":\n import asyncio\n\n asyncio.run(run())\n```\n\n### Writing MCP Clients\n\nThe SDK provides a high-level client interface for connecting to MCP servers:\n\n```python\nfrom mcp import ClientSession, StdioServerParameters, types\nfrom mcp.client.stdio import stdio_client\n\n# Create server parameters for stdio connection\nserver_params = StdioServerParameters(\n command=\"python\", # Executable\n args=[\"example_server.py\"], # Optional command line arguments\n env=None, # Optional environment variables\n)\n\n\n# Optional: create a sampling callback\nasync def handle_sampling_message(\n message: types.CreateMessageRequestParams,\n) -> types.CreateMessageResult:\n return types.CreateMessageResult(\n role=\"assistant\",\n content=types.TextContent(\n type=\"text\",\n text=\"Hello, world! from model\",\n ),\n model=\"gpt-3.5-turbo\",\n stopReason=\"endTurn\",\n )\n\n\nasync def run():\n async with stdio_client(server_params) as (read, write):\n async with ClientSession(\n read, write, sampling_callback=handle_sampling_message\n ) as session:\n # Initialize the connection\n await session.initialize()\n\n # List available prompts\n prompts = await session.list_prompts()\n\n # Get a prompt\n prompt = await session.get_prompt(\n \"example-prompt\", arguments={\"arg1\": \"value\"}\n )\n\n # List available resources\n resources = await session.list_resources()\n\n # List available tools\n tools = await session.list_tools()\n\n # Read a resource\n content, mime_type = await session.read_resource(\"file://some/path\")\n\n # Call a tool\n result = await session.call_tool(\"tool-name\", arguments={\"arg1\": \"value\"})\n\n\nif __name__ == \"__main__\":\n import asyncio\n\n asyncio.run(run())\n```\n\n### MCP Primitives\n\nThe MCP protocol defines three core primitives that servers can implement:\n\n| Primitive | Control | Description | Example Use |\n|-----------|-----------------------|-----------------------------------------------------|------------------------------|\n| Prompts | User-controlled | Interactive templates invoked by user choice | Slash commands, menu options |\n| Resources | Application-controlled| Contextual data managed by the client application | File contents, API responses |\n| Tools | Model-controlled | Functions exposed to the LLM to take actions | API calls, data updates |\n\n### Server Capabilities\n\nMCP servers declare capabilities during initialization:\n\n| Capability | Feature Flag | Description |\n|-------------|------------------------------|------------------------------------|\n| `prompts` | `listChanged` | Prompt template management |\n| `resources` | `subscribe`<br/>`listChanged`| Resource exposure and updates |\n| `tools` | `listChanged` | Tool discovery and execution |\n| `logging` | - | Server logging configuration |\n| `completion`| - | Argument completion suggestions |\n\n## Documentation\n\n- [Model Context Protocol documentation](https://modelcontextprotocol.io)\n- [Model Context Protocol specification](https://spec.modelcontextprotocol.io)\n- [Officially supported servers](https://github.com/modelcontextprotocol/servers)\n\n## Contributing\n\nWe are passionate about supporting contributors of all levels of experience and would love to see you get involved in the project. See the [contributing guide](CONTRIBUTING.md) to get started.\n\n## License\n\nThis project is licensed under the MIT License - see the LICENSE file for details.\n",
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