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README.md

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@@ -67,17 +67,27 @@ The Model Context Protocol allows applications to provide context for LLMs in a
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## Installation
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We recommend using [uv](https://docs.astral.sh/uv/) to manage your Python projects:
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### Adding MCP to your python project
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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:
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```bash
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uv add "mcp[cli]"
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```
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Alternatively:
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Alternatively, for projects using pip for dependencies:
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```bash
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pip install mcp
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```
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### Running the standalone MCP development tools
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To run the mcp command with uv:
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```bash
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uv run mcp
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```
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## Quickstart
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Let's create a simple MCP server that exposes a calculator tool and some data:
@@ -89,12 +99,14 @@ from mcp.server.fastmcp import FastMCP
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# Create an MCP server
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mcp = FastMCP("Demo")
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# Add an addition tool
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@mcp.tool()
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def add(a: int, b: int) -> int:
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"""Add two numbers"""
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return a + b
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# Add a dynamic greeting resource
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@mcp.resource("greeting://{name}")
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def get_greeting(name: str) -> str:
@@ -129,34 +141,42 @@ The FastMCP server is your core interface to the MCP protocol. It handles connec
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```python
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# Add lifespan support for startup/shutdown with strong typing
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from contextlib import asynccontextmanager
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from dataclasses import dataclass
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from typing import AsyncIterator
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from mcp.server.fastmcp import FastMCP
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from fake_database import Database # Replace with your actual DB type
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from mcp.server.fastmcp import Context, FastMCP
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# Create a named server
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mcp = FastMCP("My App")
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# Specify dependencies for deployment and development
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mcp = FastMCP("My App", dependencies=["pandas", "numpy"])
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@dataclass
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class AppContext:
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db: Database # Replace with your actual DB type
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db: Database
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@asynccontextmanager
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async def app_lifespan(server: FastMCP) -> AsyncIterator[AppContext]:
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"""Manage application lifecycle with type-safe context"""
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# Initialize on startup
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db = await Database.connect()
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try:
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# Initialize on startup
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await db.connect()
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yield AppContext(db=db)
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finally:
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# Cleanup on shutdown
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await db.disconnect()
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# Pass lifespan to server
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mcp = FastMCP("My App", lifespan=app_lifespan)
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# Access type-safe lifespan context in tools
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@mcp.tool()
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def query_db(ctx: Context) -> str:
@@ -170,11 +190,17 @@ def query_db(ctx: Context) -> str:
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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:
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```python
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from mcp.server.fastmcp import FastMCP
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mcp = FastMCP("My App")
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@mcp.resource("config://app")
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def get_config() -> str:
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"""Static configuration data"""
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return "App configuration here"
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@mcp.resource("users://{user_id}/profile")
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def get_user_profile(user_id: str) -> str:
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"""Dynamic user data"""
@@ -186,10 +212,17 @@ def get_user_profile(user_id: str) -> str:
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Tools let LLMs take actions through your server. Unlike resources, tools are expected to perform computation and have side effects:
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```python
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import httpx
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from mcp.server.fastmcp import FastMCP
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mcp = FastMCP("My App")
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@mcp.tool()
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def calculate_bmi(weight_kg: float, height_m: float) -> float:
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"""Calculate BMI given weight in kg and height in meters"""
192-
return weight_kg / (height_m ** 2)
224+
return weight_kg / (height_m**2)
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@mcp.tool()
195228
async def fetch_weather(city: str) -> str:
@@ -204,16 +237,22 @@ async def fetch_weather(city: str) -> str:
204237
Prompts are reusable templates that help LLMs interact with your server effectively:
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```python
240+
from mcp.server.fastmcp import FastMCP, types
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242+
mcp = FastMCP("My App")
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@mcp.prompt()
208246
def review_code(code: str) -> str:
209247
return f"Please review this code:\n\n{code}"
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211250
@mcp.prompt()
212-
def debug_error(error: str) -> list[Message]:
251+
def debug_error(error: str) -> list[types.Message]:
213252
return [
214-
UserMessage("I'm seeing this error:"),
215-
UserMessage(error),
216-
AssistantMessage("I'll help debug that. What have you tried so far?")
253+
types.UserMessage("I'm seeing this error:"),
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types.UserMessage(error),
255+
types.AssistantMessage("I'll help debug that. What have you tried so far?"),
217256
]
218257
```
219258

@@ -225,6 +264,9 @@ FastMCP provides an `Image` class that automatically handles image data:
225264
from mcp.server.fastmcp import FastMCP, Image
226265
from PIL import Image as PILImage
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267+
mcp = FastMCP("My App")
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228270
@mcp.tool()
229271
def create_thumbnail(image_path: str) -> Image:
230272
"""Create a thumbnail from an image"""
@@ -240,6 +282,9 @@ The Context object gives your tools and resources access to MCP capabilities:
240282
```python
241283
from mcp.server.fastmcp import FastMCP, Context
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285+
mcp = FastMCP("My App")
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243288
@mcp.tool()
244289
async def long_task(files: list[str], ctx: Context) -> str:
245290
"""Process multiple files with progress tracking"""
@@ -312,16 +357,19 @@ from mcp.server.fastmcp import FastMCP
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313358
mcp = FastMCP("Echo")
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360+
315361
@mcp.resource("echo://{message}")
316362
def echo_resource(message: str) -> str:
317363
"""Echo a message as a resource"""
318364
return f"Resource echo: {message}"
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320367
@mcp.tool()
321368
def echo_tool(message: str) -> str:
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"""Echo a message as a tool"""
323370
return f"Tool echo: {message}"
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325373
@mcp.prompt()
326374
def echo_prompt(message: str) -> str:
327375
"""Create an echo prompt"""
@@ -333,20 +381,21 @@ def echo_prompt(message: str) -> str:
333381
A more complex example showing database integration:
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335383
```python
336-
from mcp.server.fastmcp import FastMCP
337384
import sqlite3
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386+
from mcp.server.fastmcp import FastMCP
387+
339388
mcp = FastMCP("SQLite Explorer")
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341391
@mcp.resource("schema://main")
342392
def get_schema() -> str:
343393
"""Provide the database schema as a resource"""
344394
conn = sqlite3.connect("database.db")
345-
schema = conn.execute(
346-
"SELECT sql FROM sqlite_master WHERE type='table'"
347-
).fetchall()
395+
schema = conn.execute("SELECT sql FROM sqlite_master WHERE type='table'").fetchall()
348396
return "\n".join(sql[0] for sql in schema if sql[0])
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398+
350399
@mcp.tool()
351400
def query_data(sql: str) -> str:
352401
"""Execute SQL queries safely"""
@@ -368,20 +417,27 @@ For more control, you can use the low-level server implementation directly. This
368417
from contextlib import asynccontextmanager
369418
from typing import AsyncIterator
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420+
from fake_database import Database # Replace with your actual DB type
421+
422+
from mcp.server import Server
423+
424+
371425
@asynccontextmanager
372426
async def server_lifespan(server: Server) -> AsyncIterator[dict]:
373427
"""Manage server startup and shutdown lifecycle."""
428+
# Initialize resources on startup
429+
db = await Database.connect()
374430
try:
375-
# Initialize resources on startup
376-
await db.connect()
377431
yield {"db": db}
378432
finally:
379433
# Clean up on shutdown
380434
await db.disconnect()
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# Pass lifespan to server
383438
server = Server("example-server", lifespan=server_lifespan)
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385441
# Access lifespan context in handlers
386442
@server.call_tool()
387443
async def query_db(name: str, arguments: dict) -> list:
@@ -396,14 +452,15 @@ The lifespan API provides:
396452
- Type-safe context passing between lifespan and request handlers
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398454
```python
399-
from mcp.server.lowlevel import Server, NotificationOptions
400-
from mcp.server.models import InitializationOptions
401455
import mcp.server.stdio
402456
import mcp.types as types
457+
from mcp.server.lowlevel import NotificationOptions, Server
458+
from mcp.server.models import InitializationOptions
403459

404460
# Create a server instance
405461
server = Server("example-server")
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463+
407464
@server.list_prompts()
408465
async def handle_list_prompts() -> list[types.Prompt]:
409466
return [
@@ -412,18 +469,16 @@ async def handle_list_prompts() -> list[types.Prompt]:
412469
description="An example prompt template",
413470
arguments=[
414471
types.PromptArgument(
415-
name="arg1",
416-
description="Example argument",
417-
required=True
472+
name="arg1", description="Example argument", required=True
418473
)
419-
]
474+
],
420475
)
421476
]
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423479
@server.get_prompt()
424480
async def handle_get_prompt(
425-
name: str,
426-
arguments: dict[str, str] | None
481+
name: str, arguments: dict[str, str] | None
427482
) -> types.GetPromptResult:
428483
if name != "example-prompt":
429484
raise ValueError(f"Unknown prompt: {name}")
@@ -433,14 +488,12 @@ async def handle_get_prompt(
433488
messages=[
434489
types.PromptMessage(
435490
role="user",
436-
content=types.TextContent(
437-
type="text",
438-
text="Example prompt text"
439-
)
491+
content=types.TextContent(type="text", text="Example prompt text"),
440492
)
441-
]
493+
],
442494
)
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496+
444497
async def run():
445498
async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
446499
await server.run(
@@ -452,12 +505,14 @@ async def run():
452505
capabilities=server.get_capabilities(
453506
notification_options=NotificationOptions(),
454507
experimental_capabilities={},
455-
)
456-
)
508+
),
509+
),
457510
)
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512+
459513
if __name__ == "__main__":
460514
import asyncio
515+
461516
asyncio.run(run())
462517
```
463518

@@ -466,18 +521,22 @@ if __name__ == "__main__":
466521
The SDK provides a high-level client interface for connecting to MCP servers:
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468523
```python
469-
from mcp import ClientSession, StdioServerParameters
524+
from mcp import ClientSession, StdioServerParameters, types
470525
from mcp.client.stdio import stdio_client
471526

472527
# Create server parameters for stdio connection
473528
server_params = StdioServerParameters(
474-
command="python", # Executable
475-
args=["example_server.py"], # Optional command line arguments
476-
env=None # Optional environment variables
529+
command="python", # Executable
530+
args=["example_server.py"], # Optional command line arguments
531+
env=None, # Optional environment variables
477532
)
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534+
535+
479536
# Optional: create a sampling callback
480-
async def handle_sampling_message(message: types.CreateMessageRequestParams) -> types.CreateMessageResult:
537+
async def handle_sampling_message(
538+
message: types.CreateMessageRequestParams,
539+
) -> types.CreateMessageResult:
481540
return types.CreateMessageResult(
482541
role="assistant",
483542
content=types.TextContent(
@@ -488,17 +547,23 @@ async def handle_sampling_message(message: types.CreateMessageRequestParams) ->
488547
stopReason="endTurn",
489548
)
490549

550+
551+
491552
async def run():
492553
async with stdio_client(server_params) as (read, write):
493-
async with ClientSession(read, write, sampling_callback=handle_sampling_message) as session:
554+
async with ClientSession(
555+
read, write, sampling_callback=handle_sampling_message
556+
) as session:
494557
# Initialize the connection
495558
await session.initialize()
496559

497560
# List available prompts
498561
prompts = await session.list_prompts()
499562

500563
# Get a prompt
501-
prompt = await session.get_prompt("example-prompt", arguments={"arg1": "value"})
564+
prompt = await session.get_prompt(
565+
"example-prompt", arguments={"arg1": "value"}
566+
)
502567

503568
# List available resources
504569
resources = await session.list_resources()
@@ -512,8 +577,10 @@ async def run():
512577
# Call a tool
513578
result = await session.call_tool("tool-name", arguments={"arg1": "value"})
514579

580+
515581
if __name__ == "__main__":
516582
import asyncio
583+
517584
asyncio.run(run())
518585
```
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