use ASGI-transport httpx client by default, to enable easier connection between MCP server and FastAPI app, without requiring base_url and without requiring the FastAPI app to actually run.

Simplify usage examples as well.
Update README.

Author: shahar4499

README.md

@@ -48,23 +48,14 @@ from fastapi_mcp import FastApiMCP
 
 app = FastAPI()
 
-mcp = FastApiMCP(
-    app,
-
-    # Optional parameters
-    name="My API MCP",
-    description="My API description",
-    base_url="http://localhost:8000",
-)
+mcp = FastApiMCP(app)
 
 # Mount the MCP server directly to your FastAPI app
 mcp.mount()
 ```
 
 That's it! Your auto-generated MCP server is now available at `https://app.base.url/mcp`.
 
-> **Note on `base_url`**: While `base_url` is optional, it is highly recommended to provide it explicitly. The `base_url` tells the MCP server where to send API requests when tools are called. Without it, the library will attempt to determine the URL automatically, which may not work correctly in deployed environments where the internal and external URLs differ.
-
 ## Tool Naming
 
 FastAPI-MCP uses the `operation_id` from your FastAPI routes as the MCP tool names. When you don't specify an `operation_id`, FastAPI auto-generates one, but these can be cryptic.
@@ -102,7 +93,6 @@ app = FastAPI()
 mcp = FastApiMCP(
     app,
     name="My API MCP",
-    base_url="http://localhost:8000",
     describe_all_responses=True,     # Include all possible response schemas in tool descriptions
     describe_full_response_schema=True  # Include full JSON schema in tool descriptions
 )
@@ -178,10 +168,7 @@ api_app = FastAPI()
 mcp_app = FastAPI()
 
 # Create MCP server from the API app
-mcp = FastApiMCP(
-    api_app,
-    base_url="http://api-host:8001",  # The URL where the API app will be running
-)
+mcp = FastApiMCP(api_app)
 
 # Mount the MCP server to the separate app
 mcp.mount(mcp_app)

examples/filtered_tools_example.py

@@ -1,54 +1,53 @@
 from examples.shared.apps import items
 from examples.shared.setup import setup_logging
 
+from fastapi import FastAPI
 from fastapi_mcp import FastApiMCP
 
 setup_logging()
 
+app = FastAPI()
+app.include_router(items.router)
+
 # Example demonstrating how to filter MCP tools by operation IDs and tags
 
 # Filter by including specific operation IDs
 include_operations_mcp = FastApiMCP(
-    items.app,
+    app,
     name="Item API MCP - Included Operations",
     description="MCP server showing only specific operations",
-    base_url="http://localhost:8000",
     include_operations=["get_item", "list_items"],
 )
 
 # Filter by excluding specific operation IDs
 exclude_operations_mcp = FastApiMCP(
-    items.app,
+    app,
     name="Item API MCP - Excluded Operations",
     description="MCP server showing all operations except the excluded ones",
-    base_url="http://localhost:8000",
     exclude_operations=["create_item", "update_item", "delete_item"],
 )
 
 # Filter by including specific tags
 include_tags_mcp = FastApiMCP(
-    items.app,
+    app,
     name="Item API MCP - Included Tags",
     description="MCP server showing operations with specific tags",
-    base_url="http://localhost:8000",
     include_tags=["items"],
 )
 
 # Filter by excluding specific tags
 exclude_tags_mcp = FastApiMCP(
-    items.app,
+    app,
     name="Item API MCP - Excluded Tags",
     description="MCP server showing operations except those with specific tags",
-    base_url="http://localhost:8000",
     exclude_tags=["search"],
 )
 
 # Combine operation IDs and tags (include mode)
 combined_include_mcp = FastApiMCP(
-    items.app,
+    app,
     name="Item API MCP - Combined Include",
     description="MCP server showing operations by combining include filters",
-    base_url="http://localhost:8000",
     include_operations=["delete_item"],
     include_tags=["search"],
 )
@@ -69,4 +68,4 @@
     print(" - /include-tags-mcp: Only operations with the 'items' tag")
     print(" - /exclude-tags-mcp: All operations except those with the 'search' tag")
     print(" - /combined-include-mcp: Operations with 'search' tag or delete_item operation")
-    uvicorn.run(items.app, host="0.0.0.0", port=8000)
+    uvicorn.run(items.router, host="0.0.0.0", port=8000)

examples/full_schema_description_example.py

@@ -1,17 +1,21 @@
 from examples.shared.apps import items
 from examples.shared.setup import setup_logging
 
+from fastapi import FastAPI
 from fastapi_mcp import FastApiMCP
 
 setup_logging()
 
 
+app = FastAPI()
+app.include_router(items.router)
+
+
 # Add MCP server to the FastAPI app
 mcp = FastApiMCP(
-    items.app,
+    app,
     name="Item API MCP",
     description="MCP server for the Item API",
-    base_url="http://localhost:8000",
     describe_full_response_schema=True,  # Describe the full response JSON-schema instead of just a response example
     describe_all_responses=True,  # Describe all the possible responses instead of just the success (2XX) response
 )
@@ -22,4 +26,4 @@
 if __name__ == "__main__":
     import uvicorn
 
-    uvicorn.run(items.app, host="0.0.0.0", port=8000)
+    uvicorn.run(items.router, host="0.0.0.0", port=8000)

examples/mount_specific_router_example.py

@@ -1,28 +1,31 @@
 from examples.shared.apps import items
 from examples.shared.setup import setup_logging
 
-from fastapi import APIRouter
+from fastapi import FastAPI, APIRouter
 from fastapi_mcp import FastApiMCP
 
 setup_logging()
 
 
-router = APIRouter(prefix="/other/route")
-items.app.include_router(router)
+other_router = APIRouter(prefix="/other/route")
+
+app = FastAPI()
+app.include_router(items.router)
+app.include_router(other_router)
 
 mcp = FastApiMCP(
-    items.app,
+    app,
     name="Item API MCP",
     description="MCP server for the Item API",
     base_url="http://localhost:8000",
 )
 
 # Mount the MCP server to a specific router.
 # It will now only be available at `/other/route/mcp`
-mcp.mount(router)
+mcp.mount(other_router)
 
 
 if __name__ == "__main__":
     import uvicorn
 
-    uvicorn.run(items.app, host="0.0.0.0", port=8000)
+    uvicorn.run(items.router, host="0.0.0.0", port=8000)

examples/reregister_tools_example.py

@@ -1,26 +1,26 @@
 from examples.shared.apps import items
 from examples.shared.setup import setup_logging
 
+from fastapi import FastAPI
 from fastapi_mcp import FastApiMCP
 
 setup_logging()
 
 
+app = FastAPI()
+app.include_router(items.router)
+
+
 # Add MCP server to the FastAPI app
-mcp = FastApiMCP(
-    items.app,
-    name="Item API MCP",
-    description="MCP server for the Item API",
-    base_url="http://localhost:8000",
-)
+mcp = FastApiMCP(app)
 
 
 # MCP server
 mcp.mount()
 
 
 # This endpoint will not be registered as a tool, since it was added after the MCP instance was created
-@items.app.get("/new/endpoint/", operation_id="new_endpoint", response_model=dict[str, str])
+@items.router.get("/new/endpoint/", operation_id="new_endpoint", response_model=dict[str, str])
 async def new_endpoint():
     return {"message": "Hello, world!"}
 
@@ -32,4 +32,4 @@ async def new_endpoint():
 if __name__ == "__main__":
     import uvicorn
 
-    uvicorn.run(items.app, host="0.0.0.0", port=8000)
+    uvicorn.run(items.router, host="0.0.0.0", port=8000)

examples/separate_server_example.py

@@ -1,5 +1,4 @@
 from fastapi import FastAPI
-import asyncio
 import uvicorn
 
 from examples.shared.apps import items
@@ -10,35 +9,23 @@
 setup_logging()
 
 
-MCP_SERVER_HOST = "localhost"
-MCP_SERVER_PORT = 8000
-ITEMS_API_HOST = "localhost"
-ITEMS_API_PORT = 8001
+app = FastAPI()
+app.include_router(items.router)
 
 
 # Take the FastAPI app only as a source for MCP server generation
-mcp = FastApiMCP(
-    items.app,
-    base_url=f"http://{ITEMS_API_HOST}:{ITEMS_API_PORT}",  # Note how the base URL is the **Items API** URL, not the MCP server URL
-)
+mcp = FastApiMCP(app)
+
 
 # And then mount the MCP server to a separate FastAPI app
 mcp_app = FastAPI()
 mcp.mount(mcp_app)
 
 
-def run_items_app():
-    uvicorn.run(items.app, port=ITEMS_API_PORT)
-
-
-def run_mcp_app():
-    uvicorn.run(mcp_app, port=MCP_SERVER_PORT)
-
-
-# The MCP server depends on the Items API to be available, so we need to run both.
-async def main():
-    await asyncio.gather(asyncio.to_thread(run_items_app), asyncio.to_thread(run_mcp_app))
-
-
+# Run the MCP server separately from the original FastAPI app.
+# It still works 🚀
+# Your original API is **not exposed**, only via the MCP server.
 if __name__ == "__main__":
-    asyncio.run(main())
+    import uvicorn
+
+    uvicorn.run(mcp_app, host="0.0.0.0", port=8000)

examples/shared/apps/items.py

@@ -2,20 +2,14 @@
 Simple example of using FastAPI-MCP to add an MCP server to a FastAPI app.
 """
 
-from fastapi import FastAPI, HTTPException, Query
+from fastapi import APIRouter, HTTPException, Query
 from pydantic import BaseModel
 from typing import List, Optional
 
 
-# Create a simple FastAPI app
-app = FastAPI(
-    title="Example API",
-    description="A simple example API with integrated MCP server",
-    version="0.1.0",
-)
+router = APIRouter()
 
 
-# Define some models
 class Item(BaseModel):
     id: int
     name: str
@@ -24,12 +18,10 @@ class Item(BaseModel):
     tags: List[str] = []
 
 
-# In-memory database
 items_db: dict[int, Item] = {}
 
 
-# Define some endpoints
-@app.get("/items/", response_model=List[Item], tags=["items"], operation_id="list_items")
+@router.get("/items/", response_model=List[Item], tags=["items"], operation_id="list_items")
 async def list_items(skip: int = 0, limit: int = 10):
     """
     List all items in the database.
@@ -39,7 +31,7 @@ async def list_items(skip: int = 0, limit: int = 10):
     return list(items_db.values())[skip : skip + limit]
 
 
-@app.get("/items/{item_id}", response_model=Item, tags=["items"], operation_id="get_item")
+@router.get("/items/{item_id}", response_model=Item, tags=["items"], operation_id="get_item")
 async def read_item(item_id: int):
     """
     Get a specific item by its ID.
@@ -51,7 +43,7 @@ async def read_item(item_id: int):
     return items_db[item_id]
 
 
-@app.post("/items/", response_model=Item, tags=["items"], operation_id="create_item")
+@router.post("/items/", response_model=Item, tags=["items"], operation_id="create_item")
 async def create_item(item: Item):
     """
     Create a new item in the database.
@@ -62,7 +54,7 @@ async def create_item(item: Item):
     return item
 
 
-@app.put("/items/{item_id}", response_model=Item, tags=["items"], operation_id="update_item")
+@router.put("/items/{item_id}", response_model=Item, tags=["items"], operation_id="update_item")
 async def update_item(item_id: int, item: Item):
     """
     Update an existing item.
@@ -77,7 +69,7 @@ async def update_item(item_id: int, item: Item):
     return item
 
 
-@app.delete("/items/{item_id}", tags=["items"], operation_id="delete_item")
+@router.delete("/items/{item_id}", tags=["items"], operation_id="delete_item")
 async def delete_item(item_id: int):
     """
     Delete an item from the database.
@@ -91,7 +83,7 @@ async def delete_item(item_id: int):
     return {"message": "Item deleted successfully"}
 
 
-@app.get("/items/search/", response_model=List[Item], tags=["search"], operation_id="search_items")
+@router.get("/items/search/", response_model=List[Item], tags=["search"], operation_id="search_items")
 async def search_items(
     q: Optional[str] = Query(None, description="Search query string"),
     min_price: Optional[float] = Query(None, description="Minimum price"),
@@ -105,27 +97,23 @@ async def search_items(
     """
     results = list(items_db.values())
 
-    # Filter by search query
     if q:
         q = q.lower()
         results = [
             item for item in results if q in item.name.lower() or (item.description and q in item.description.lower())
         ]
 
-    # Filter by price range
     if min_price is not None:
         results = [item for item in results if item.price >= min_price]
     if max_price is not None:
         results = [item for item in results if item.price <= max_price]
 
-    # Filter by tags
     if tags:
         results = [item for item in results if all(tag in item.tags for tag in tags)]
 
     return results
 
 
-# Add sample data
 sample_items = [
     Item(id=1, name="Hammer", description="A tool for hammering nails", price=9.99, tags=["tool", "hardware"]),
     Item(id=2, name="Screwdriver", description="A tool for driving screws", price=7.99, tags=["tool", "hardware"]),