MassGen exposes 6 background job management tools with severely limited schema documentation and generic descriptions. All tool names follow the verb_resource pattern (get_, list_, cancel_, wait_, start_), which is positive. However, descriptions are generic and lack LLM-optimized context ('Get status of a background tool execution job' is 54 chars but provides no guidance on when to call it vs alternatives). Input schemas are present for all tools, but parameter descriptions are minimal ('Job identifier to query' lacks format, constraints, or expected patterns). No output schemas are documented anywhere in the visible code, LLMs cannot infer what fields to expect from response objects. The risk classification (WRITE vs READ_ONLY) is a positive security signal, but tool definitions lack idempotency guarantees, error handling guidance, or integration context. The 'arguments' parameter in start_background_tool is a bare object with no schema validation, inviting hallucinated or invalid tool invocations.

• Document output schema for each tool. For get_background_tool_status, specify: { job_id: string, status: 'pending'|'running'|'completed'|'failed', progress_percent?: number, error_message?: string, ... }. This enables LLMs to chain calls.
• Expand tool descriptions to 80-150 chars, including: (1) what the tool does, (2) when to call it, (3) required prerequisites, (4) what it returns. Example: 'Get the execution status and result of a background job. Use this after starting a job (start_background_tool) or when waiting fails. Returns job_id, status (pending|running|completed|failed), progress, and any error message.'
• Add schema validation to the 'arguments' parameter in start_background_tool. Instead of a bare object, either: (a) enumerate valid tool names and their argument schemas, or (b) document that arguments must match the schema of the referenced tool_name.
• Add constraint descriptions to all string parameters: 'job_id: a unique identifier returned by start_background_tool (UUID format, e.g. a1b2c3d4-e5f6-47a8-9b0c-1d2e3f4a5b6c)'.
• Document timeout_seconds bounds: 'timeout_seconds: max seconds to wait (1-3600; default 300). If timeout is exceeded, tool returns status=timed_out with partial results if available.'
• Add idempotency statement to read-only tools: 'This tool is fully idempotent, safe to retry on network failures without side effects.'
• Document error cases and recovery paths: 'If start_background_tool returns job_name_invalid error, call list_background_tools() to see available tools. If status is failed, call get_background_tool_result() to retrieve the error message.'

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry