mirror of
https://github.com/PrefectHQ/fastmcp.git
synced 2026-08-09 15:19:10 +02:00
baced6281c* Always emit a tool title, derived from name when unset Some MCP clients (e.g. ChatGPT) drop tools with no `title` instead of falling back to `name` for display as the spec allows. Deriving a default title in Tool.to_mcp_tool() fixes this for every tool built on top of it, including the search-transform, code-mode, and session proxy tools that never set one explicitly. Fixes #4414 * Derive fallback title from the overridden name, document it Addresses Codex review on #4694. * Resolve title precedence from effective overrides * Normalize mapping annotations before deriving the title
129 lines
4.1 KiB
Python
129 lines
4.1 KiB
Python
import pytest
|
|
from mcp_types import ToolAnnotations
|
|
|
|
from fastmcp.tools.base import Tool
|
|
|
|
|
|
class TestToolTitle:
|
|
"""Tests for tool title functionality."""
|
|
|
|
def test_tool_with_title(self):
|
|
"""Test that tools can have titles and they appear in MCP conversion."""
|
|
|
|
def calculate(x: int, y: int) -> int:
|
|
"""Calculate the sum of two numbers."""
|
|
return x + y
|
|
|
|
tool = Tool.from_function(
|
|
calculate,
|
|
name="calc",
|
|
title="Advanced Calculator Tool",
|
|
description="Custom description",
|
|
)
|
|
|
|
assert tool.name == "calc"
|
|
assert tool.title == "Advanced Calculator Tool"
|
|
assert tool.description == "Custom description"
|
|
|
|
# Test MCP conversion includes title
|
|
mcp_tool = tool.to_mcp_tool()
|
|
assert mcp_tool.name == "calc"
|
|
assert (
|
|
hasattr(mcp_tool, "title") and mcp_tool.title == "Advanced Calculator Tool"
|
|
)
|
|
|
|
def test_tool_without_title(self):
|
|
"""Test that tools without an explicit title derive one from the name.
|
|
|
|
Some MCP clients (e.g. ChatGPT) drop tools with no `title` rather
|
|
than falling back to `name` as the spec allows, so FastMCP always
|
|
emits a derived title on the wire instead of relying on that
|
|
fallback.
|
|
"""
|
|
|
|
def multiply(a: int, b: int) -> int:
|
|
return a * b
|
|
|
|
tool = Tool.from_function(multiply)
|
|
|
|
assert tool.name == "multiply"
|
|
assert tool.title is None
|
|
|
|
mcp_tool = tool.to_mcp_tool()
|
|
assert mcp_tool.name == "multiply"
|
|
assert mcp_tool.title == "Multiply"
|
|
|
|
def test_derived_title_follows_name_override(self):
|
|
"""The derived title should reflect a `name` override, not the original name."""
|
|
|
|
def multiply(a: int, b: int) -> int:
|
|
return a * b
|
|
|
|
tool = Tool.from_function(multiply, name="multiply_tool")
|
|
|
|
mcp_tool = tool.to_mcp_tool(name="renamed_tool")
|
|
assert mcp_tool.name == "renamed_tool"
|
|
assert mcp_tool.title == "Renamed Tool"
|
|
|
|
@pytest.mark.parametrize(
|
|
"annotations",
|
|
[ToolAnnotations(title="Custom"), {"title": "Custom"}],
|
|
ids=["object", "dict"],
|
|
)
|
|
def test_annotations_override_beats_derived_title(self, annotations):
|
|
"""An `annotations` override still outranks the name-derived title."""
|
|
|
|
def multiply(a: int, b: int) -> int:
|
|
return a * b
|
|
|
|
tool = Tool.from_function(multiply)
|
|
|
|
mcp_tool = tool.to_mcp_tool(annotations=annotations)
|
|
assert mcp_tool.title == "Custom"
|
|
|
|
def test_tool_title_priority(self):
|
|
"""Test that explicit title takes priority over annotations.title."""
|
|
|
|
def divide(x: int, y: int) -> float:
|
|
"""Divide two numbers."""
|
|
return x / y
|
|
|
|
# Test with both explicit title and annotations.title
|
|
annotations = ToolAnnotations(title="Annotation Title")
|
|
tool = Tool.from_function(
|
|
divide,
|
|
name="div",
|
|
title="Explicit Title",
|
|
annotations=annotations,
|
|
)
|
|
|
|
assert tool.title == "Explicit Title"
|
|
assert tool.annotations is not None
|
|
assert tool.annotations.title == "Annotation Title"
|
|
|
|
# Explicit title should take priority
|
|
mcp_tool = tool.to_mcp_tool()
|
|
assert mcp_tool.title == "Explicit Title"
|
|
|
|
def test_tool_annotations_title_fallback(self):
|
|
"""Test that annotations.title is used when no explicit title is provided."""
|
|
|
|
def modulo(x: int, y: int) -> int:
|
|
"""Get modulo of two numbers."""
|
|
return x % y
|
|
|
|
# Test with only annotations.title (no explicit title)
|
|
annotations = ToolAnnotations(title="Annotation Title")
|
|
tool = Tool.from_function(
|
|
modulo,
|
|
name="mod",
|
|
annotations=annotations,
|
|
)
|
|
|
|
assert tool.title is None
|
|
assert tool.annotations is not None
|
|
assert tool.annotations.title == "Annotation Title"
|
|
|
|
# Should fall back to annotations.title
|
|
mcp_tool = tool.to_mcp_tool()
|
|
assert mcp_tool.title == "Annotation Title"
|