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

With no annotations provided, the description carries the behavioral disclosure burden and does well: it states the flat credit cost, explains that long jobs return a job_id to poll with get_job, and warns that result links expire in one hour. These are important operational traits beyond the schema. It still omits auth requirements and error behavior, so it is not fully comprehensive.

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 tightly written sentences, with the core purpose front-loaded before operational caveats. Every sentence earns its place: purpose, cost, async polling, and link expiry. No filler or 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?

There is no output schema and no annotations, so the description must carry most context. It adequately covers purpose, modes, cost, async behavior, polling, and link expiry. It could still say more about return structure or authentication, but for a tool of this complexity the description is largely complete.

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 67%, so some parameters are documented in the schema while mode and format lack descriptions there. The description adds useful meaning by explaining the frames-vs-contact-sheet modes and the chosen-times vs evenly-spaced frame selection. It does not cover width, format, or the count/at_seconds override relationship beyond what is already in the schema.

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 a specific verb and resource: grabbing still frames from a video or building a contact sheet. It clearly separates the two output modes, so an agent can tell what the tool does. However, it does not name or contrast against sibling tools like sprite_sheet, shot_list, or make_slideshow, so it falls short of full 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?

The description explains the two output modes but gives no explicit guidance on when to choose this tool over alternatives. There are no when-to-use conditions, exclusions, or named alternatives. The agent must infer usage context from the purpose alone.

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