samples: improve dynamic server with params descriptions

Author: cristipufu

samples/mcp-dynamic-server/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "mcp-dynamic-server"
-version = "0.0.3"
+version = "0.0.5"
 description = "Dynamic tools MCP Server"
 authors = [{ name = "John Doe" }]
 dependencies = [

samples/mcp-dynamic-server/server.py

@@ -5,17 +5,43 @@
 # Initialize the MCP server
 mcp = FastMCP("Self-Extending MCP Server")
 
+built_in_tools = {
+    "get_tools": {
+        "description": "Get a list of all available tools in the MCP server.",
+        "parameters": {}
+    },
+    "add_tool": {
+        "description": "Add a new tool to the MCP server.",
+        "parameters": {
+            "name": "Name of the tool",
+            "code": "Python code implementing the tool function",
+            "description": "Description of what the tool does",
+            "param_descriptions": "Dictionary of parameter names to descriptions (optional)"
+        }
+    },
+    "call_tool": {
+        "description": "Call a registered tool with the given arguments.",
+        "parameters": {
+            "name": "Name of the tool to call",
+            "args": "Dictionary of arguments to pass to the tool"
+        }
+    }
+}
 
 # Tool registry to track dynamically added tools
 class ToolRegistry:
     def __init__(self):
         self.tools = {}  # name -> function
         self.metadata = {}  # name -> metadata
 
-    def register(self, name: str, func: Callable, description: str):
+    def register(self, name: str, func: Callable, description: str, param_descriptions: Dict[str, str] = None):
         """Register a new tool in the registry."""
         self.tools[name] = func
-        self.metadata[name] = {"name": name, "description": description}
+        self.metadata[name] = {
+            "name": name,
+            "description": description,
+            "parameters": param_descriptions or {}
+        }
 
     def get_tool(self, name: str) -> Optional[Callable]:
         """Get a tool by name."""
@@ -49,19 +75,23 @@ def get_tools() -> Dict[str, Any]:
     try:
         tools = registry.list_tools()
 
-        # Add the built-in tools
-        built_in_tools = ["get_tools", "add_tool", "call_tool"]
-
         # Combine built-in tools with dynamic tools
-        all_tools = [{"name": tool, "built_in": True} for tool in built_in_tools]
+        all_tools = []
+        for name, info in built_in_tools.items():
+            all_tools.append({
+                "name": name,
+                "description": info["description"],
+                "parameters": info["parameters"],
+                "built_in": True
+            })
+
         for tool in tools:
-            all_tools.append(
-                {
-                    "name": tool["name"],
-                    "description": tool["description"],
-                    "built_in": False,
-                }
-            )
+            all_tools.append({
+                "name": tool["name"],
+                "description": tool["description"],
+                "parameters": tool["parameters"],
+                "built_in": False
+            })
 
         return {"status": "success", "tools": all_tools}
     except Exception as e:
@@ -70,13 +100,14 @@ def get_tools() -> Dict[str, Any]:
 
 # Core functionality: Add a new tool
 @mcp.tool()
-def add_tool(name: str, code: str, description: str) -> Dict[str, Any]:
+def add_tool(name: str, code: str, description: str, param_descriptions: Dict[str, str] = None) -> Dict[str, Any]:
     """Add a new tool to the MCP server.
 
     Args:
         name: Name of the tool
         code: Python code implementing the tool function
         description: Description of what the tool does
+        param_descriptions: Dictionary of parameter names to descriptions
 
     Returns:
         Dictionary with operation status
@@ -109,9 +140,16 @@ def add_tool(name: str, code: str, description: str) -> Dict[str, Any]:
                 }
 
             # Register the tool with our registry
-            registry.register(name, func, description)
+            registry.register(name, func, description, param_descriptions)
 
-            return {"status": "success", "message": f"Tool '{name}' added successfully"}
+            # Get the parameter information to return
+            params = registry.get_metadata(name)["parameters"]
+
+            return {
+                "status": "success",
+                "message": f"Tool '{name}' added successfully",
+                "parameters": params
+            }
 
         except SyntaxError as e:
             return {
@@ -139,27 +177,35 @@ def call_tool(name: str, args: Dict[str, Any]) -> Dict[str, Any]:
     """
     try:
         # Check if it's a built-in tool
-        if name in ["get_tools", "add_tool", "call_tool"]:
+        if name in built_in_tools:
             return {
                 "status": "error",
                 "message": f"Cannot call built-in tool '{name}' using call_tool",
+                "note": f"Use the {name} function directly instead of call_tool",
+                "parameters": built_in_tools[name]["parameters"]
             }
 
         # Get the tool
         tool = registry.get_tool(name)
 
         if not tool:
-            return {"status": "error", "message": f"Tool '{name}' not found"}
+            return {
+                "status": "error",
+                "message": f"Tool '{name}' not found",
+                "available_tools": [t["name"] for t in registry.list_tools()]
+            }
 
         # Call the tool with the provided arguments
         try:
             result = tool(**args)
             return result
         except TypeError as e:
             # Likely an argument mismatch
+            params = registry.get_metadata(name)["parameters"]
             return {
                 "status": "error",
                 "message": f"Argument error calling tool '{name}': {str(e)}",
+                "expected_parameters": params
             }
         except Exception as e:
             return {