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

Annotations already declare idempotentHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds two things annotations do not: it consumes AI credits and it is asynchronous, returning a job handle. That is genuine value beyond the 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?

Two sentences, zero padding, and the primary action is front-loaded ahead of the cost and follow-up details. Every clause earns its place.

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 an output schema present, the description needn't document the return payload, and it correctly gestures at the async job anyway. It is essentially complete for a fire-and-poll generation tool; only explicit alternative-routing guidance is missing.

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% (mood enum, prompt, durationSeconds 10-120, idempotencyKey retry semantics, workspaceId default), so the schema carries the full parameter burden. The description adds no syntax or format detail, which is the baseline 3 case.

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: 'Queue a background music track into the BlitzReels media library.' That distinguishes it from generation_sound_create and generation_voiceover_create by naming the artifact as music, though it never explicitly contrasts with those siblings.

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 gives useful follow-up routing ('returns a job to poll with generation_jobs_get') and warns that credits are spent, but offers no when-to-use guidance versus generation_sound_create, generation_video_create, or media_import_url. Usage is implied rather than stated.

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