Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover readOnly, idempotent, non-destructive, non-open-world. The description adds auth requirements (active narrador X subscription, narrador:x scope or nrd_x_* API key) and return shape (signed audioUrl, duration, wordTimings) — all beyond structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded purpose, then return fields, then auth. Slightly dense with return-value enumeration, but every sentence carries signal and nothing is redundant.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema, so the description responsibly enumerates returned fields (generationId, audioUrl, duration, wordTimings). Auth and the triggering sibling are covered, leaving only edge cases like expiry of the signed URL unaddressed.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the generationId param is already documented with format uui d and source. The description reinforces the linkage ('if generate_x_audio was called earlier') but adds no syntax beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Specific verb+resource: fetches the X generation result (audio and metadata). The description clearly distinguishes this retrieval tool from its sibling generate_x_audio, which produces the generation in the first place.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use: 'to retrieve a generation if generate_x_audio was called earlier or to re-fetch audio.' This names the sibling that produces the input and gives a concrete trigger condition.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.