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

Goes well past the annotations by disclosing the async job contract (returns {id, status}, poll getApiJob), the credit cost (3 per call), the 7-day provenance requirement, and the return shape (only an audio URL, .mp3 or .wav, no video). It also explains the side effect that audio is attached to the spritesheet and resurfaces as audio_url in listGenerations.

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-loads the core action and input provenance, then layers exclusions, output shape, and job/credit mechanics in a logical order. It is dense and long-ish, and the request_id/listGenerations sentences could be trimmed, but nothing is redundant filler.

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 an async, nested-parameter, credit-consuming generation tool with no output schema, the description covers eligibility, alternatives, async polling, credit cost, return value, and downstream visibility. Nothing an agent needs to invoke it and interpret the result 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 coverage is 100%, so the baseline is 3; the description earns more by explaining the provenance constraint on spritesheet_video_url (must come from one of four named tools, within 7 days) and the idempotency plus 'must not reuse a request_id' rule for request_id. It adds less on prompt, which is left as the schema states it.

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?

Opens with a specific verb+resource ('Generate a sound effect for a previously generated spritesheet animation') and immediately ties its input to four named sibling tools (animateSprite, animateSpriteKeyframes, transferMotion, editSpritesheet), which cleanly separates it from createSoundEffect and createMusic. An agent can pick this over its siblings without opening a schema.

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 NOT to call it: 'Spritesheets generated with the hydra model already come with audio_url, so only call this for forge / forge-pixel output or to replace hydra's sound.' It also excludes external videos and stale spritesheets (older than 7 days), so the eligibility conditions are fully enumerated.

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