contact-sheet

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

Without annotations, the description carries the full burden of behavioral transparency. It states that the tool renders frames and composites them into a single image, implying a non-destructive read operation. It does not mention side effects, auth needs, or rate limits, but the behavior is straightforward and clearly described. A score of 5 would require explicit statements about no side effects or read-only nature.

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 extremely concise (two sentences) and front-loaded with the main purpose. The first sentence states the action and outcome, the second provides usage context and a use case. Every sentence is necessary and 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?

Given the tool's simplicity and full schema coverage, the description is fairly complete. It explains what the tool does, how to select the composition, and the purpose. However, it omits details about the output image format (e.g., labeling scheme, grid layout) and does not mention that it is a read-only operation. With no output schema, these details would be helpful.

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%, so baseline is 3. The description adds minimal extra value: for 'comp' it explains it can be omitted for active comp, and for others it restates schema info. It does not provide additional context beyond what the schema already describes, such as examples or constraints.

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 purpose: rendering N frames sampled across a composition's duration and compositing them into a single labeled thumbnail grid. It uses specific verbs ('render', 'composite') and resource ('composition timeline') and distinguishes from sibling tools like 'see-frame' by emphasizing the overview nature ('one image instead of many').

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: it is for perceiving motion, timing, and easing cheaply. It explains how to select the composition (by name, index, or leave empty for active comp). However, it does not explicitly state when not to use this tool (e.g., for high-resolution frames or specific frame extraction) or mention alternative tools, though siblings are available.

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