Namespace Transform

Prefix component names to prevent conflicts

New in version 3.0.0

The Namespace transform prefixes all component names, preventing conflicts when composing multiple servers.

Tools and prompts receive an underscore-separated prefix. Resources and templates receive a path-segment prefix in their URIs.

Component	Original	With Namespace("api")
Tool	my_tool	api_my_tool
Prompt	my_prompt	api_my_prompt
Resource	data://info	data://api/info
Template	data://{id}	data://api/{id}

The most common use is through the mount() method’s namespace parameter.

from fastmcp import FastMCP

weather = FastMCP("Weather")
calendar = FastMCP("Calendar")

@weather.tool
def get_data() -> str:
    return "Weather data"

@calendar.tool
def get_data() -> str:
    return "Calendar data"

# Without namespacing, these would conflict
main = FastMCP("Main")
main.mount(weather, namespace="weather")
main.mount(calendar, namespace="calendar")

# Clients see: weather_get_data, calendar_get_data

You can also apply namespacing directly using the Namespace transform.

from fastmcp import FastMCP
from fastmcp.server.transforms import Namespace

mcp = FastMCP("Server")

@mcp.tool
def greet(name: str) -> str:
    return f"Hello, {name}!"

# Namespace all components
mcp.add_transform(Namespace("api"))

# Tool is now: api_greet