Preview animation (contact sheet)

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

Annotations flag destructiveHint=true and readOnlyHint=false; the description clarifies exactly what that means in practice — a file is written only when outputPath is supplied, and an existing file is never replaced unless overwrite is set. That is genuine added context beyond the annotation. Minor gap: it doesn't say whether rendering perturbs the open composition's playhead/state, which matters for idempotentHint=true.

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?

Three tight sentences: purpose and output shape first, defaults second, alternative tool and write-safety last. Nothing is wasted or buried.

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 zero-required-parameter preview tool with full schema coverage and annotations, the description covers output shape, defaults, file-write safety, and sibling routing. Only the interaction between `times` and `frames` (mutually exclusive selection of sampling) is left to the schema, which is a small residual gap.

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 all nine parameters already carry defaults and constraints. The description restates the frame-count and work-area defaults and the outputPath/overwrite relationship, which is useful reinforcement but adds no semantics the schema lacks.

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?

Specific verb ('render several frames') plus specific output form (one grid image with per-cell time/frame labels), and it explicitly distinguishes itself from ae_render_frame. An agent knows exactly what this produces without opening the 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 the use case ('judge motion, timing and easing, not just a single frame') and names the alternative with the selecting condition ('For one frame in detail use ae_render_frame'). This is explicit when-to-use routing, not inference.

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