refactor: extract BaseMetadata base class for name/title fields

Add BaseMetadata base class to provide common name and title fields for
consistency with TypeScript SDK implementation. This centralizes the
field definitions for Implementation, Tool, Resource, ResourceTemplate,
and Prompt classes.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: felixweinberger

src/mcp/types.py

@@ -196,12 +196,19 @@ class EmptyResult(Result):
     """A response that indicates success but carries no data."""
 
 
-class Implementation(BaseModel):
-    """Describes the name and version of an MCP implementation."""
+class BaseMetadata(BaseModel):
+    """Base class for entities with name and optional title fields."""
 
     name: str
+    """The programmatic name of the entity."""
+
     title: str | None = None
-    """A human-readable title for the implementation."""
+    """An optional human-readable title for the entity."""
+
+
+class Implementation(BaseMetadata):
+    """Describes the name and version of an MCP implementation."""
+
     version: str
     model_config = ConfigDict(extra="allow")
 
@@ -384,15 +391,11 @@ class Annotations(BaseModel):
     model_config = ConfigDict(extra="allow")
 
 
-class Resource(BaseModel):
+class Resource(BaseMetadata):
     """A known resource that the server is capable of reading."""
 
     uri: Annotated[AnyUrl, UrlConstraints(host_required=False)]
     """The URI of this resource."""
-    name: str
-    """A human-readable name for this resource."""
-    title: str | None = None
-    """A human-readable title for this resource."""
     description: str | None = None
     """A description of what this resource represents."""
     mimeType: str | None = None
@@ -413,18 +416,14 @@ class Resource(BaseModel):
     model_config = ConfigDict(extra="allow")
 
 
-class ResourceTemplate(BaseModel):
+class ResourceTemplate(BaseMetadata):
     """A template description for resources available on the server."""
 
     uriTemplate: str
     """
     A URI template (according to RFC 6570) that can be used to construct resource
     URIs.
     """
-    name: str
-    """A human-readable name for the type of resource this template refers to."""
-    title: str | None = None
-    """A human-readable title for the type of resource this template refers to."""
     description: str | None = None
     """A human-readable description of what this template is for."""
     mimeType: str | None = None
@@ -607,13 +606,9 @@ class PromptArgument(BaseModel):
     model_config = ConfigDict(extra="allow")
 
 
-class Prompt(BaseModel):
+class Prompt(BaseMetadata):
     """A prompt or prompt template that the server offers."""
 
-    name: str
-    """The name of the prompt or prompt template."""
-    title: str | None = None
-    """A human-readable title for the prompt."""
     description: str | None = None
     """An optional description of what this prompt provides."""
     arguments: list[PromptArgument] | None = None
@@ -816,13 +811,9 @@ class ToolAnnotations(BaseModel):
     model_config = ConfigDict(extra="allow")
 
 
-class Tool(BaseModel):
+class Tool(BaseMetadata):
     """Definition for a tool the client can call."""
 
-    name: str
-    """The name of the tool."""
-    title: str | None = None
-    """A human-readable title for the tool."""
     description: str | None = None
     """A human-readable description of the tool."""
     inputSchema: dict[str, Any]