Namespace Transform - Fastmcp

import { VersionBadge } from '/snippets/version-badge.mdx'

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.

python

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.

python

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