server-memory: Output schema has additionalProperties: false but response includes 'type' field #3210

Description

When using the @modelcontextprotocol/server-memory package with the MCP Python client library, the search_nodes tool fails validation when entities exist in the knowledge graph.

Steps to Reproduce

1. Use @modelcontextprotocol/server-memory via npx
2. Create an entity: create_entities with {"entities": [{"name": "Test", "entityType": "Person", "observations": ["test obs"]}]}
3. Search for the entity: search_nodes with {"query": "Test"}

Expected Behavior

The search result should pass validation and return successfully.

Actual Behavior

The MCP Python client throws a validation error:
RuntimeError: Invalid structured content returned by tool search_nodes: Additional properties are not allowed ('type' was unexpected)

On instance['entities'][0]: {'type': 'entity', 'name': 'Test', 'entityType': 'Person', 'observations': ['test obs']}

Root Cause

The search_nodes tool's output schema declares additionalProperties: false for entity items, but the actual response includes a type: "entity" field that isn't in the schema definition.

Suggested Fix

Either:

1. Add type to the output schema properties, or
2. Remove additionalProperties: false from the schema, or
3. Remove the type field from the response

Environment

• @modelcontextprotocol/server-memory via npx (latest)
• MCP Python client library
• Python 3.12