Video thumbnails

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

Beyond the annotations, the description discloses that provider scopes, locks and credits apply, that confirmation is mandatory before provider execution, and that only one submission is allowed. These are meaningful operational traits (cost consumption, irreversibility of submission) that align with and extend the destructiveHint/openWorldHint annotations.

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 definition is brief and front-loads the endpoint and confirmation rule with no filler. It is arguably too terse for a nested-payload video operation, but nothing is wasted.

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 destructive, credit-consuming video tool with a nested payload object and no output schema, the description covers confirmation and cost but says nothing about the result (e.g. number of thumbnails returned, URLs, or job/polling behavior). It is minimally adequate but leaves real gaps.

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 the schema already documents account, confirm, payload and payload_file in detail. The description only echoes the confirmation requirement already implied by the confirm parameter, adding no new syntax or format detail, so the baseline 3 applies.

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 opens with the raw endpoint string "POST /v5/tools/video_thumbnails," which essentially restates the tool name rather than stating what the operation produces. It never says in plain language that it extracts or generates thumbnail images from a video, so an agent depends entirely on inferring intent from the name and siblings.

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?

There is no guidance on when to use this tool versus the many sibling video tools (trim_video, create_gif_preview, create_video_slideshow, etc.), nor any stated precondition beyond the generic confirmation note. The agent must infer use cases on its own.

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