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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds genuinely new context beyond them: the shape of the result (slug, params, per-call price in prepaid credits) and the side effect that every miss is logged for catalog expansion.

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 tightly written sentences with no filler; the capability statement comes first and the return/side-effect detail second. Every clause carries information an agent cannot get from the structured fields.

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?

There is no output schema, but the description compensates by naming the returned fields and the logging side effect, which is enough for an agent to call it correctly. Minor gap: it doesn't say how results are ranked or bounded, which matters for an openWorld search.

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 single query parameter is already documented as 'What kind of API you need, in plain words.' The description adds no search syntax, matching behavior, or example queries, so the baseline 3 is appropriate.

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 verb and resource ('Search the apifare catalog of ready-to-call APIs') and enumerates example categories (web search, scraping, weather), so the agent knows exactly what is being searched. It is clearly distinct from action-oriented siblings like call_api or vendor_call, though it never names them 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?

Usage is implied rather than stated: an agent can infer this is the discovery step before invoking an API. There is no explicit when-to-use or when-not-to-use guidance (e.g., 'use call_api to actually invoke a slug you find'), and no exclusion conditions are given.

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