test: Add test for non-ASCII character handling in FastMCP tools

Author: dsp-ant

tests/server/fastmcp/test_server.py

@@ -30,6 +30,29 @@ async def test_create_server(self):
         mcp = FastMCP()
         assert mcp.name == "FastMCP"
 
+    @pytest.mark.anyio
+    async def test_non_ascii_description(self):
+        """Test that FastMCP handles non-ASCII characters in descriptions correctly"""
+        mcp = FastMCP()
+
+        @mcp.tool(description="🌟 This tool uses emojis and UTF-8 characters: á é í ó ú ñ 漢字 🎉")
+        def hello_world(name: str = "世界") -> str:
+            return f"¡Hola, {name}! 👋"
+
+        async with client_session(mcp._mcp_server) as client:
+            tools = await client.list_tools()
+            assert len(tools.tools) == 1
+            tool = tools.tools[0]
+            assert "🌟" in tool.description
+            assert "漢字" in tool.description
+            assert "🎉" in tool.description
+
+            result = await client.call_tool("hello_world", {})
+            assert len(result.content) == 1
+            content = result.content[0]
+            assert isinstance(content, TextContent)
+            assert "¡Hola, 世界! 👋" == content.text
+
     @pytest.mark.anyio
     async def test_add_tool_decorator(self):
         mcp = FastMCP()