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

With no annotations supplied, the description carries the full burden and does so well: it discloses per-call cost (€0.002 charged to the API key in Authorization: Bearer), the classification taxonomy, the returned fields, and the evaluation boundary. It does not cover failure behavior (inaccessible URLs, unsupported formats) or rate limits, which keeps it below a 5.

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 text is compact and front-loaded: capability, verdict values, exclusions, cost/auth, then parameters. The trailing "Parameters — url: image url" is slightly wasted given the schema, but nothing else is padded.

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 one-parameter classification tool with an output schema, the description covers taxonomy, cost, auth, and scope boundaries. The remaining gap is the nullable/optional url semantics and error behavior, which matters modestly since the only input is optional.

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 coverage is 0% for the single parameter, so the description must compensate; it only offers "url: image url." That does clarify the URL must point at an image rather than a page, which is real value, but it never explains that the parameter is optional/nullable or what happens when it is omitted.

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?

"Nudity check" names the operation and resource, and the description goes further by listing the outputs (safe/suggestive/explicit verdict, score, faces, boxes) and explicitly excluding weapons, drugs, and text. That exclusion distinguishes it from generic moderation or profanity_filter siblings without naming them directly.

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 phrase "for marketplaces and bots" implies a usage context, and the exclusions tell an agent when NOT to use it. However, there is no explicit routing guidance such as "use profanity_filter for text" or "use url_safety for link reputation," so the agent must infer the alternative.

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