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

Annotations declare non-read-only, non-idempotent, non-destructive, closed-world, and the description adds genuinely useful context the annotations cannot: a fixed $0.05 per-call price, which is a real side effect and justifies readOnlyHint=false. However, it says nothing about input size limits, what happens with malformed specs, or what the summary output looks like, so the behavioral picture is only partially filled in.

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?

Three short, front-loaded sentences with no filler; the capability, the price, and the use case appear in that order. The final sentence is a fragment rather than a clause, which is slightly informal but costs no clarity.

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 analysis tool with no output schema, the description does a reasonable job by enumerating the output sections (endpoints, auth, schemas, errors) and disclosing pricing. Missing only edge-case handling guidance such as spec size limits or behavior on invalid YAML/JSON.

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?

There is a single required parameter with 100% schema description coverage ("OpenAPI JSON or YAML text."), so the schema already carries the semantics and the baseline is 3. The description adds no constraint such as size limits, whether a URL is accepted versus raw text, or supported OpenAPI versions.

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 (Summarise) and a specific resource set (endpoints, auth, schemas, errors from an OpenAPI document), so the agent can distinguish it from adjacent API tools like fikra_diagnose_api_error or fikra_generate_api_tests. It stops short of naming the nearest sibling explicitly, so it is clear but not fully differentiated.

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?

"Understanding a large API before integrating" implies a usage context, but there is no explicit when-to-use rule, no when-not-to-use rule, and no alternative named (e.g. explain_json or diagnose_api_error for smaller or error-specific cases). The agent must infer routing from the resource description alone.

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