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

Beyond the annotations (readOnlyHint false, non-idempotent), the description discloses the one-hour URL lifetime, the 'give them the URL' human handoff, the single-file/format/size/duration limits, and the rights confirmation the user makes on the page. It stops short of saying whether calling again issues a fresh page or invalidates a prior URL — relevant given idempotentHint=false — and says nothing about rate limits.

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?

Two sentences, front-loaded with the action and the returned artifact, then the constraints, then the follow-up chain. Every clause (formats, 60s, 4 MB, rights confirmation, chat-app restriction) carries an operational decision the agent would otherwise have to discover by failure.

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?

With no parameters, no output schema and only coarse annotations, the description carries the full burden and does so: it explains what is returned, how long it lives, what the user must comply with, and which tools to call afterward. An agent has everything needed to invoke it and handle the response.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline is 4. The description instead spends its words on the returned URL contract, which is the only input-like decision an agent faces here.

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 names a specific verb and resource (returns an upload_page_url so the user can upload their own voice recording) and immediately scopes it with constraints: one file, MP3/WAV/M4A/OGG, 60s, 4 MB. The clause 'Use in chat apps, which can't upload files' implicitly separates it from the direct-upload sibling upload_audio, and the follow-up tools are named explicitly.

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?

It states exactly when to use this tool (chat apps that cannot upload files, user supplying their own recording) and gives the full follow-up sequence: check_audio_upload when the user says they're done, then create_video_from_audio or set_scene_audio with the audio_upload_id. This is an explicit when-and-what-next routing, not an implied one.

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