Document pydantic.ValidationError in client Raises sections

The client surfaces pydantic.ValidationError when a server returns a
result that does not conform to the negotiated protocol version. List it
in the Raises sections of ClientSession.send_request and the
Client.call_tool / get_prompt / read_resource loops.

Author: maxisbey

src/mcp/client/client.py

@@ -629,6 +629,8 @@ async def read_resource(
         Raises:
             InputRequiredRoundsExceededError: `input_required_max_rounds` exhausted.
             MCPError: A callback returned `ErrorData` for an embedded input request.
+            pydantic.ValidationError: The server returned a result that does not
+                conform to the negotiated protocol version.
         """
 
         async def retry(r: InputResponses | None, s: str | None) -> ReadResourceResult | InputRequiredResult:
@@ -711,6 +713,8 @@ async def call_tool(
         Raises:
             InputRequiredRoundsExceededError: `input_required_max_rounds` exhausted.
             MCPError: A callback returned `ErrorData` for an embedded input request.
+            pydantic.ValidationError: The server returned a result that does not
+                conform to the negotiated protocol version.
         """
 
         async def retry(r: InputResponses | None, s: str | None) -> CallToolResult | InputRequiredResult | Result:
@@ -787,6 +791,8 @@ async def get_prompt(
         Raises:
             InputRequiredRoundsExceededError: `input_required_max_rounds` exhausted.
             MCPError: A callback returned `ErrorData` for an embedded input request.
+            pydantic.ValidationError: The server returned a result that does not
+                conform to the negotiated protocol version.
         """
 
         async def retry(r: InputResponses | None, s: str | None) -> GetPromptResult | InputRequiredResult:

src/mcp/client/session.py

@@ -452,6 +452,8 @@ async def send_request(
             MCPError: Error response, read timeout, or connection closed.
             RuntimeError: Called before entering the context manager.
             ValueError: The request declares `name_param` but its params carry no string name.
+            pydantic.ValidationError: The server returned a result that does not
+                conform to the negotiated protocol version.
         """
         data = request.model_dump(by_alias=True, mode="json", exclude_none=True)
         method: str = data["method"]