fastmcp.types

Reusable type annotations for FastMCP tool parameters.

These types can be used in tool function signatures to influence how parameters are presented in UIs (e.g. fastmcp dev apps) and serialized in JSON Schema.

Example:

from fastmcp import FastMCP
from fastmcp.types import Textarea

mcp = FastMCP("demo")

@mcp.tool()
def run_query(sql: Textarea) -> str:
    ...