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

Annotations only declare readOnlyHint=false, so the description carries most of the burden. It adds real behavioral value by disclosing the metered cost model ('$0.001/sec at provider cost') and the fact that the audio is generated from the scene's own footage rather than a text prompt alone. It doesn't say whether the result is attached to the timeline, whether regenerating replaces prior audio, or how it scales with scene length.

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 cost signal and followed by the disambiguation clause. No filler and nothing out of order.

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 three-parameter, cost-metered generation tool with no output schema, the definition covers purpose, alternative, and pricing. The remaining gap is what the call produces — an audio element on the scene, a new track, an updateable asset — which matters for a mutation with only a readOnlyHint=false annotation.

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%, including the useful 'Omit for natural ambience' note on prompt, so the baseline is 3. The description adds framing (sound is derived from the scene) but no parameter-level detail beyond what the schema already states.

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?

States a specific verb and resource ('Generate sound effects and ambience FOR a scene') plus the mechanism ('from its own footage (foley)'). It explicitly names the nearest sibling, generate_music, and explains the difference, so an agent can separate the two without inspecting either 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?

Gives clear context (per-scene foley, derived from the shot's own footage) and an explicit contrast with generate_music. It does not cover the other adjacent alternatives in the crowded studio namespace, such as add_audio_to_timeline, enhance_audio, or generate_voiceover, so exclusions are incomplete.

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