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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and openness are covered structurally. The description adds one genuine behavioral fact beyond them: the call is 'Free,' which matters for a paid-API catalog. It says nothing about error behavior for invalid ids, rate limits, or whether coverage/price can be null, so the added value is real but thin.

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?

One sentence plus a one-word cost note, with the returned content front-loaded and zero filler. The telegraphic fragment style ('Input parameters (JSON Schema), coverage and price...') is dense but slightly awkward as prose.

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 single-parameter, read-only lookup with no output schema, the description covers what is returned (parameter schema, coverage, price) and where the input id comes from. The only real gap is that it never explains the handoff to call_api, which an agent would need to complete the workflow.

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 100% and the schema already gives an example id, so the baseline would be 3. The description goes slightly beyond by tying the parameter's value domain to search_apis, telling the agent where a valid id originates rather than leaving it to guess.

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 names the exact resource (one API id) and the exact payload returned: input parameters as JSON Schema, coverage, and price. That distinguishes it from call_api (invocation) and search_apis (discovery), though it never names call_api as the contrasting sibling. An agent can tell what this tool yields without opening the schema.

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 'one API id from search_apis' establishes the prerequisite workflow: ids come from search_apis, and this tool resolves a single id. It stops short of stating when to prefer this over call_api or what to do with an unknown id, so there is context but no explicit exclusions.

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