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

No annotations exist, so the description carries the full burden, and it does disclose the two non-obvious traits: mandatory per-call cost (0.001 USDC via x402) and the returned fields. It omits how many matches are returned, what the ranking is based on, whether results are stable across calls, and any rate/error behavior — gaps an agent would want before committing paid calls.

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 sentences, front-loaded with the capability and output shape, then free alternatives, then price. Every sentence is load-bearing and nothing 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?

With only two optional params, no output schema, and no annotations, the description covers what an agent most needs: what it returns and that it costs money. The recommendation to omit paymentProof for the 402 handshake lives in the schema, which is fine. It falls short only on result-set size and ranking basis for a paid discovery call.

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% with rich property text, including the full two-step payment flow for paymentProof, so the schema already does the heavy lifting. The description only echoes 'plain-language task' and the price, adding no syntax, granularity, or quality guidance for the task string. 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 — 'Ranks the tools in this API against a plain-language task' — and names exactly what comes back (method, URL, price, input schema). This is unmistakably the meta/discovery tool among ~50 siblings that each do concrete work, so an agent can separate it from address_check, token_audit, etc. without opening any 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?

Usage is only implied: an agent can infer it should call this when it doesn't know which endpoint fits a task. The 'free catalog is at /llms.txt and /openapi.json' line gestures at an alternative, but the description never states when to pay 0.001 USDC versus just reading the free catalog — the single most important routing question for this tool is left unanswered.

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