product · inferred from evidence
FastMCP
A framework or library used to build MCP servers, mentioned as commonly not setting `additionalProperties: false`.
- n8n 1.119.1 breaks MCP tool calls with "toolCallId: Unexpected keyword argument" validation error
This was a regression in n8n 1.119.1: the update added strict validation of MCP tool-call arguments, so the `toolCallId` parameter n8n itself injects got rejected by tools whose schemas do not set `additionalProperties: false` (which is com