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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuinely new context: no auth/API key, free with no quota, reads the same snapshot as search_catalog, and the exact error for an unknown id. It also discloses the full shape of the returned record.

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?

Purpose and sibling routing are front-loaded in the first two sentences, and the remaining text earns its place given there is no output schema. The return-field enumeration is long and reads as a dense run-on, which slightly hurts scannability.

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 no output schema, the description fully compensates by enumerating the returned fields (id, provider, category, advertised_price, quality_test, paid_receipts, latest, history_summary, page_url) and the error path. Nothing an agent needs to call or interpret this tool is missing.

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 documents case-sensitivity and gives examples, so the baseline is 3. The description adds value by pointing to where ids come from (search_catalog or lookup results) and by specifying the failure mode for an unknown/missing id, which the schema does not.

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 ('Fetch the complete catalog record for one known service id') and immediately distinguishes itself from siblings by naming search_catalog (find ids) and lookup (rank services / receipts). An agent can route correctly 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?

Explicit when-to-use routing: search_catalog to find ids, lookup to rank services, and lookup with endpoint=<id> when receipts with tx/Basescan links are needed. This is a textbook when/when-not/alternative statement.

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