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

With no annotations, the description carries the full burden and discloses key behaviors: constant-rate retiming, trim unchanged, timeline length changes in proportion to speed, and audio time-stretched with pitch preserved. These are behavioral consequences beyond what the schema or annotations would convey.

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 two sentences, front-loads the core purpose, and each clause earns its place: purpose, speed scale+range, behavioral consequence, alternative tool. No filler or repetition.

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 simple constant-rate mutation tool with no output schema and no annotations, the description is complete: it covers the action, the parameter's effect, side-effects on trim and length, audio handling, and sibling differentiation. Nothing an agent needs to call it correctly 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?

Although schema coverage is 100%, the description adds meaning to the speed parameter by explaining that 0.5x doubles the clip's timeline length and 2x halves it, and that speed is interpreted as a constant factor. This goes beyond the schema's bare 'constant playback rate' description, helping an agent choose appropriate values.

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 the exact action ('Play a clip slower or faster at a CONSTANT rate'), names the resource ('a clip'), and clearly distinguishes itself from sibling add_speed_keyframe, which is for changing rate. This is a specific verb+resource with explicit sibling differentiation.

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 explicitly says this is 'the normal way to retime a clip' and provides a concrete alternative condition: 'Use add_speed_keyframe instead only when the rate must CHANGE over the clip (a ramp).' This gives clear when-to-use and when-not-to-use guidance.

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