analyze_thumbnail

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes the tool's behavior: it returns metadata (not analysis), specifies the exact data fields provided (URL, resolution, file size), and clarifies the version limitation ('In v1 this is metadata only'). However, it lacks details on error handling, rate limits, or authentication needs.

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 front-loaded with the core purpose in the first sentence, followed by clarifying details. Every sentence adds value: the first defines the output, and the second sets scope limitations. There is no redundant or wasted text, making it highly efficient.

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 low complexity (single parameter, no output schema, no annotations), the description is largely complete. It clearly states what the tool does and its limitations. However, without an output schema, it could benefit from more detail on return format or error cases, though the metadata fields are specified.

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 100% description coverage, with the video_id parameter fully documented in the schema. The description does not add any parameter-specific information beyond what the schema provides, such as format examples or constraints, so it meets the baseline of 3 for high schema coverage without extra value.

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 specific action ('Returns basic image metadata') and resource ('for a video's thumbnail'), with explicit output details (URL, resolution, file size). It distinguishes itself from potential vision analysis tools by stating 'metadata only — no vision model analysis,' which helps differentiate it from siblings like get_video_details or get_tag_analysis that might involve deeper analysis.

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 context for when to use this tool: to obtain thumbnail metadata without vision analysis. It implicitly suggests alternatives by noting the limitation ('no vision model analysis'), but does not explicitly name sibling tools or specify when-not-to-use scenarios beyond this scope.

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