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Agentor enables you to build a custom MCP Server as a FastAPI app. You can integrate it with your existing FastAPI app or deploy it as a standalone MCP Server. LiteMCP

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LiteMCP - Lightweight MCP Server

To build MCP Servers with Agentor, you can use the LiteMCP class. 
from agentor.mcp import LiteMCP

# Create the app
app = LiteMCP()

# Register a tool
@app.tool(description="Get weather")
def get_weather(location: str) -> str:
    return f"Weather in {location}: Sunny"

# Run the server
if __name__ == "__main__":
    app.run()

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LiteMCP vs FastMCP

LiteMCP has a more transparent design and FastAPI primitives such as middlewares and dependency injection are immediately available, while FastMCP requires mounting as a sub-application, diverging from standard FastAPI primitives.
FeatureLiteMCPFastMCP
Integration PatternNative ASGI appRequires mounting
FastAPI Primitives✅ Standard patterns⚠️ Diverges (sub-app)
With Existing Backend✅ Easy⚠️ Complex
Decorator API✅ Yes✅ Yes
Custom Methods✅ Full support⚠️ Limited
Lightweight✅ Minimal deps⚠️ More deps

Connecting MCP endpoint to existing FastAPI app

Using FastMCP
from starlette.applications import Starlette
from starlette.routing import Mount
from mcp.server.fastmcp import FastMCP

mcp = FastMCP("My App")
app = Starlette(
    routes=[
        Mount("/mcp", app=mcp.streamable_http_app())  # Separate ASGI app
    ]
)
Using LiteMCP
from agentor.mcp import LiteMCP
from fastapi import FastAPI

# Create the app
app = FastAPI()
mcp = LiteMCP()
app.include_router(mcp.get_fastapi_router())  # Include MCP endpoints like a regular APIRouter

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When to Use Each

Use LiteMCP when:
  • You want to serve MCP tools alongside your existing FastAPI/Starlette backend
  • You prefer standard FastAPI patterns and routing
  • You want full control over custom JSON-RPC methods
  • You want minimal dependencies
Use FastMCP when:
  • You’re building a standalone MCP server
  • You want the official SDK implementation
  • You don’t need to integrate with existing web services

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Configuration

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Constructor Parameters

LiteMCP(
    host="0.0.0.0",  # Host to bind (for run() method)
    port=8000,  # Port to bind (for run() method)
    enable_cors=True,  # Enable CORS middleware
    name="mcp-server",  # Server name
    version="1.0.0",  # Server version
    instructions="...",  # Server instructions
    website_url="...",  # Website URL
    icons=[...],  # Server icons
    prefix="/mcp",  # MCP endpoint prefix
)

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Decorators

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@app.tool()

Register a tool that can be called by MCP clients: 
@app.tool(
    name="custom_name",  # Optional: defaults to function name
    description="Tool description",
    input_schema={...},  # Optional: auto-generated from function signature
)
def my_tool(param1: str, param2: int = 10) -> str:
    return f"Result: {param1} {param2}"

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@app.prompt()

Register a prompt template: 
@app.prompt(
    name="custom_name",  # Optional: defaults to function name
    description="Prompt description",
    arguments=[...],  # Optional: auto-generated from function signature
)
def my_prompt(context: str, style: str = "formal") -> str:
    return f"Generate a {style} response about {context}"

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@app.resource()

Register a resource that can be read by MCP clients: 
@app.resource(
    uri="resource://path",
    name="Resource Name",
    description="Resource description",
    mime_type="text/plain",
)
def my_resource(uri: str) -> str:
    return "Resource content"