feat: add execution parameter to add_tool() for task support declaration

Add ToolExecution parameter to MCPServer.add_tool(), ToolManager.add_tool(),
and Tool.from_function() to allow declaring execution.taskSupport per tool
as required by MCP spec 2025-11-25.

Also pass execution through in MCPServer.list_tools() when converting
internal Tool to MCP types.Tool.

Fixes #2156

Author: Fan

src/mcp/server/mcpserver/server.py

@@ -67,6 +67,7 @@
     TextContent,
     TextResourceContents,
     ToolAnnotations,
+    ToolExecution,
 )
 from mcp.types import Prompt as MCPPrompt
 from mcp.types import PromptArgument as MCPPromptArgument
@@ -383,6 +384,7 @@ async def list_tools(self) -> list[MCPTool]:
                 annotations=info.annotations,
                 icons=info.icons,
                 _meta=info.meta,
+                execution=info.execution,
             )
             for info in tools
         ]
@@ -465,6 +467,7 @@ def add_tool(
         icons: list[Icon] | None = None,
         meta: dict[str, Any] | None = None,
         structured_output: bool | None = None,
+        execution: ToolExecution | None = None,
     ) -> None:
         """Add a tool to the server.
 
@@ -483,6 +486,8 @@ def add_tool(
                 - If None, auto-detects based on the function's return type annotation
                 - If True, creates a structured tool (return type annotation permitting)
                 - If False, unconditionally creates an unstructured tool
+            execution: Optional ToolExecution for declaring task support per MCP spec
+                (e.g. ToolExecution(taskSupport="optional"))
         """
         self._tool_manager.add_tool(
             fn,
@@ -493,6 +498,7 @@ def add_tool(
             icons=icons,
             meta=meta,
             structured_output=structured_output,
+            execution=execution,
         )
 
     def remove_tool(self, name: str) -> None:

src/mcp/server/mcpserver/tools/base.py

@@ -13,7 +13,7 @@
 from mcp.server.mcpserver.utilities.func_metadata import FuncMetadata, func_metadata
 from mcp.shared.exceptions import UrlElicitationRequiredError
 from mcp.shared.tool_name_validation import validate_and_warn_tool_name
-from mcp.types import Icon, ToolAnnotations
+from mcp.types import Icon, ToolAnnotations, ToolExecution
 
 if TYPE_CHECKING:
     from mcp.server.context import LifespanContextT, RequestT
@@ -36,6 +36,7 @@ class Tool(BaseModel):
     annotations: ToolAnnotations | None = Field(None, description="Optional annotations for the tool")
     icons: list[Icon] | None = Field(default=None, description="Optional list of icons for this tool")
     meta: dict[str, Any] | None = Field(default=None, description="Optional metadata for this tool")
+    execution: ToolExecution | None = Field(default=None, description="Optional execution properties for task support")
 
     @cached_property
     def output_schema(self) -> dict[str, Any] | None:
@@ -53,6 +54,7 @@ def from_function(
         icons: list[Icon] | None = None,
         meta: dict[str, Any] | None = None,
         structured_output: bool | None = None,
+        execution: ToolExecution | None = None,
     ) -> Tool:
         """Create a Tool from a function."""
         func_name = name or fn.__name__
@@ -87,6 +89,7 @@ def from_function(
             annotations=annotations,
             icons=icons,
             meta=meta,
+            execution=execution,
         )
 
     async def run(

src/mcp/server/mcpserver/tools/tool_manager.py

@@ -6,7 +6,7 @@
 from mcp.server.mcpserver.exceptions import ToolError
 from mcp.server.mcpserver.tools.base import Tool
 from mcp.server.mcpserver.utilities.logging import get_logger
-from mcp.types import Icon, ToolAnnotations
+from mcp.types import Icon, ToolAnnotations, ToolExecution
 
 if TYPE_CHECKING:
     from mcp.server.context import LifespanContextT, RequestT
@@ -51,6 +51,7 @@ def add_tool(
         icons: list[Icon] | None = None,
         meta: dict[str, Any] | None = None,
         structured_output: bool | None = None,
+        execution: ToolExecution | None = None,
     ) -> Tool:
         """Add a tool to the server."""
         tool = Tool.from_function(
@@ -62,6 +63,7 @@ def add_tool(
             icons=icons,
             meta=meta,
             structured_output=structured_output,
+            execution=execution,
         )
         existing = self._tools.get(tool.name)
         if existing: