McpMixin for decorating Class methods

sample.py

@@ -0,0 +1,46 @@
+"""Sample code for FastMCP."""
+
+from src.fastmcp import FastMCP
+from src.fastmcp.utilities.registerable import (
+    McpRegisterable,
+    mcp_prompt,
+    mcp_resource,
+    mcp_tool,
+)
+
+mcp = FastMCP()
+
+
+class Sample(McpRegisterable):
+    def __init__(self, name):
+        self.name = name
+
+    @mcp_tool()
+    def first_tool(self):
+        """First tool description."""
+        return f"Executed tool {self.name}."
+
+    @mcp_resource(uri="test://test")
+    def first_resource(self):
+        """First resource description."""
+        return f"Executed resource {self.name}."
+
+    @mcp_prompt()
+    def first_prompt(self):
+        """First prompt description."""
+        return f"here's a prompt! {self.name}."
+
+
+first_sample = Sample("First")
+second_sample = Sample("Second")
+
+first_sample.register_all(mcp_server=mcp, prefix="first")
+second_sample.register_all(mcp_server=mcp, prefix="second")
+
+
+def main():
+    mcp.run("sse")
+
+
+if __name__ == "__main__":
+    main()

src/fastmcp/utilities/registerable.py

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+"""Provides a base class and decorators for easy registration of class methods with FastMCP."""
+
+from collections.abc import Callable
+from typing import TYPE_CHECKING, Any
+
+if TYPE_CHECKING:
+    from ..server import FastMCP
+
+_MCP_REGISTRATION_TOOL_ATTR = "_mcp_tool_registration"
+_MCP_REGISTRATION_RESOURCE_ATTR = "_mcp_resource_registration"
+_MCP_REGISTRATION_PROMPT_ATTR = "_mcp_prompt_registration"
+
+
+def mcp_tool(
+    name: str | None = None,
+    description: str | None = None,
+    tags: set[str] | None = None,
+) -> Callable[[Callable[..., Any]], Callable[..., Any]]:
+    """Decorator to mark a method as an MCP tool for later registration."""
+
+    def decorator(func: Callable[..., Any]) -> Callable[..., Any]:
+        call_args = {
+            "name": name or func.__name__,
+            "description": description,
+            "tags": tags,
+        }
+        call_args = {k: v for k, v in call_args.items() if v is not None}
+        setattr(func, _MCP_REGISTRATION_TOOL_ATTR, call_args)
+        return func
+
+    return decorator
+
+
+def mcp_resource(
+    uri: str,
+    *,
+    name: str | None = None,
+    description: str | None = None,
+    mime_type: str | None = None,
+    tags: set[str] | None = None,
+) -> Callable[[Callable[..., Any]], Callable[..., Any]]:
+    """Decorator to mark a method as an MCP resource for later registration."""
+
+    def decorator(func: Callable[..., Any]) -> Callable[..., Any]:
+        call_args = {
+            "uri": uri,
+            "name": name or func.__name__,
+            "description": description,
+            "mime_type": mime_type,
+            "tags": tags,
+        }
+        call_args = {k: v for k, v in call_args.items() if v is not None}
+
+        setattr(func, _MCP_REGISTRATION_RESOURCE_ATTR, call_args)
+
+        return func
+
+    return decorator
+
+
+def mcp_prompt(
+    name: str | None = None,
+    description: str | None = None,
+    tags: set[str] | None = None,
+) -> Callable[[Callable[..., Any]], Callable[..., Any]]:
+    """Decorator to mark a method as an MCP prompt for later registration."""
+
+    def decorator(func: Callable[..., Any]) -> Callable[..., Any]:
+        call_args = {
+            "name": name or func.__name__,
+            "description": description,
+            "tags": tags,
+        }
+
+        call_args = {k: v for k, v in call_args.items() if v is not None}
+
+        setattr(func, _MCP_REGISTRATION_PROMPT_ATTR, call_args)
+        return func
+
+    return decorator
+
+
+class McpRegisterable:
+    """Base class for objects that can register tools, resources, and prompts
+    with a FastMCP server instance using decorators.
+    """
+
+    def _get_methods_to_register(self, registration_type: str):
+        """Retrieves all registration info for the specified type."""
+
+        return [
+            (
+                getattr(self, method_name),
+                getattr(getattr(self, method_name), registration_type).copy(),
+            )
+            for method_name in dir(self)
+            if hasattr(getattr(self, method_name), registration_type)
+        ]
+
+    def register_tools(self, mcp_server: "FastMCP", prefix: str | None = None) -> None:
+        """Registers all methods marked with @mcp_tool with the FastMCP server.
+
+        Args:
+            mcp_server: The FastMCP server instance to register tools with.
+        """
+
+        for method, registration_info in self._get_methods_to_register(
+            _MCP_REGISTRATION_TOOL_ATTR
+        ):
+            if prefix:
+                registration_info["name"] = f"{prefix}_{registration_info['name']}"
+
+            mcp_server.add_tool(fn=method, **registration_info)
+
+    def register_resources(
+        self, mcp_server: "FastMCP", prefix: str | None = None
+    ) -> None:
+        """Registers all methods marked with @mcp_resource with the FastMCP server.
+
+        Args:
+            mcp_server: The FastMCP server instance to register resources with.
+        """
+
+        for method, registration_info in self._get_methods_to_register(
+            _MCP_REGISTRATION_RESOURCE_ATTR
+        ):
+            if prefix:
+                registration_info["name"] = f"{prefix}_{registration_info['name']}"
+                registration_info["uri"] = f"{prefix}+{registration_info['uri']}"
+
+            mcp_server.add_resource_fn(fn=method, **registration_info)
+
+    def register_prompts(
+        self, mcp_server: "FastMCP", prefix: str | None = None
+    ) -> None:
+        """Registers all methods marked with @mcp_prompt with the FastMCP server.
+
+        Args:
+            mcp_server: The FastMCP server instance to register prompts with.
+        """
+        for method, registration_info in self._get_methods_to_register(
+            _MCP_REGISTRATION_PROMPT_ATTR
+        ):
+            if prefix:
+                registration_info["name"] = f"{prefix}_{registration_info['name']}"
+
+            mcp_server.add_prompt(fn=method, **registration_info)
+
+    def register_all(
+        self,
+        mcp_server: "FastMCP",
+        prefix: str | None = None,
+        tools_prefix: str | None = None,
+        resources_prefix: str | None = None,
+        prompts_prefix: str | None = None,
+    ) -> None:
+        """Registers all marked tools, resources, and prompts."""
+        self.register_tools(mcp_server, prefix=tools_prefix or prefix)
+        self.register_resources(mcp_server, prefix=resources_prefix or prefix)
+        self.register_prompts(mcp_server, prefix=prompts_prefix or prefix)