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

No annotations are provided, so the description carries the full burden. Describing returned fields implies a read-only lookup, but it says nothing about permissions, errors for unknown ids, caching, or rate limits. It adds some value (the returned data categories) but leaves the behavioral profile largely inferred.

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 sentences, front-loaded with the return contract and followed by the one parameter's format. No filler.

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 lookup with no output schema, the description covers what is returned and what the id may be. Only error/not-found behavior is unaddressed, which is a minor gap at this complexity.

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, and it does: it explains that `id` accepts either an OpenRouter id (with a concrete example, anthropic/claude-opus-5) or a Hugging Face repo id. This is the key invocation detail and is not present in the schema.

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?

States a specific resource and the exact data returned (pricing, context length, catalog status), scoped to a single model. This clearly distinguishes it from siblings like compare_models and estimate_cost, though it never names an alternative explicitly.

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 single-model scope implies when to use it over compare_models, but there is no explicit when/when-not guidance or mention of alternatives. A caller must infer the routing from scope alone.

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