contact-sheet

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It clearly explains the process: sample frames across the duration, composite them into a labeled grid, and return a single image. It also addresses comp selection (name, 1-based index, or active comp). It does not mention timeout or resource implications, but the behavior is well-articulated.

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-loaded with the core value proposition ('See a composition's whole timeline at a glance'), followed by the method and selection instructions. Every sentence earns its place with no redundancy.

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?

No output schema or annotations exist, so the description must cover the return value and key behaviors. It does so by stating the output is a single labeled image and explaining comp selection. The remaining parameters are well-documented in the schema, and the use case is clear. Minor gaps like timeout behavior are not critical for invocation.

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 adds minimal meaning beyond the schema: it reiterates the comp selection options and clarifies '1-based index', but does not elaborate on count, maxWidth, or timeoutMs. This is sufficient since the schema already documents each parameter.

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 clearly states the tool's function: rendering N frames from a composition and compositing them into a single labeled thumbnail grid. It uses a specific verb (render/composite) and resource (composition timeline), distinguishing it from sibling tools like see-frame or get-layer-clip-frames.

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?

The description provides clear usage context ('Use this to perceive motion, timing, and easing cheaply') and explains the advantage of one image over many. It does not explicitly name alternatives or state when not to use it, but the guidance is sufficient for an AI to choose appropriately.

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