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

The description goes beyond the annotations by explaining that the subtitle source is consumed on call and cannot be re-executed, and that no additional charge applies. This is critical behavioral context for a destructive, non-idempotent operation.

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?

The description is short, front-loaded with the core purpose, and each sentence adds value: output format, completion requirement, one-time consumption, and pricing reassurance. The bilingual repetition is justified for the target audience.

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?

For a single-parameter tool, the description covers the essentials: what is returned, when it is valid, and what side effects occur. No output schema exists, but the base64 format is stated, so an agent has enough information to invoke the tool correctly.

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 description coverage is 100%, so the job_id parameter is already documented as a 32-character ID in completed state. The description adds no additional parameter-level meaning beyond that, matching the baseline for full coverage.

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?

The description states a specific verb and resource: download completed ASS subtitles as base64. It clearly distinguishes this tool from siblings like tts_jobs_status and tts_jobs_result by specifying the subtitle deliverable and the one-time nature.

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?

The description makes the intended context clear: the TTS job must be completed, and the download is a single-use operation. It does not explicitly name alternative tools or state when not to use it, but the completed-state condition is a clear usage signal.

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