media_thumbnail

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

No annotations are provided, so the description carries the full burden of behavioral disclosure, but it only reveals that the output is a single JPEG. It does not state the return format (binary, URL, or base64), the unit or semantics of `at`, or behavior on invalid media, leaving the agent to guess how a successful call is delivered.

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 single sentence is efficient with zero waste, but the brevity reflects under-specification rather than disciplined, front-loaded structure. At 0% schema coverage, the description cannot afford to be this spare.

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 3-parameter tool with no annotations and no output schema, this description leaves essential invocation details unanswered: how the JPEG is delivered, what `at` means, and how width constraints affect the result. It is barely sufficient for an agent to call the tool correctly and safely.

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 0%, so the description must compensate for the undocumented `media_id`, `at`, and `width` parameters, yet it is completely silent on all three. An agent cannot learn what `at` controls, in what units, or how `width` is applied (aspect-ratio preservation vs. cropping) from either the schema or the description.

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 uses a specific verb ('extract') with a specific resource ('a single JPEG thumbnail') and names the output format, making the core operation clear. However, it does not explicitly distinguish it from siblings like `media_extract_frames` and `export_thumbnail_set`; the word 'single' only implies the contrast rather than stating it.

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 gives no guidance on when to use this tool versus alternatives. It never mentions `media_extract_frames` for multiple frames or `export_thumbnail_set` for a set of thumbnails, and provides no use-case context such as previews or contact sheets. An agent must infer appropriateness purely from the tool name.

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