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

Annotations already establish the read-only, non-destructive profile, so the bar is low. The description adds a useful behavioral detail—this listing does not trigger rendering—and makes clear the result is stills from the catalog, not a rendered video.

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?

Two short sentences, both substantive; no redundant filler. The front-loaded purpose is immediately followed by a useful constraint.

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 parameterless read-only list with an output schema, the description covers the essential purpose and non-rendering behavior. It is slightly incomplete in resolving the actors/stills terminology and providing no sibling guidance, but nothing required to invoke it 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?

The input schema has zero parameters, so the baseline is 4. There is nothing for the description to add, and it rightly omits parameter detail.

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 names a specific operation ('List ... catalog stills') and adds a clarifying negative ('Does not render'), which sets it apart from rendering-related siblings. However, it never explicitly says 'actors,' so the resource being listed is slightly ambiguous against the tool name.

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?

No guidance is given for when to choose this tool over its many sibling list/get/research tools. 'Does not render' only forecloses rendering use cases; it does not name alternatives or selection conditions.

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