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

Annotations already cover the read-only/idempotent profile, but the description adds material context the annotations do not: no auth or API key, no quota or per-client limit, and the actual data source (local bundled catalog.json vs. published catalog.json on remote /mcp). It also discloses the error behavior for non-numeric max_price_usd/limit and the no-match case.

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?

Front-loaded with purpose and sibling routing before the detailed return-field enumeration. The field list is long but earns most of its place because no output schema exists; still, the enumeration is denser than needed for a selection decision.

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 carries the full burden of documenting returns and does so exhaustively ({count, results, generated_at, note, methodology_url}, per-result fields, and the empty-result case), plus the auth/quota envelope. An agent has everything needed to call and interpret it.

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%, so the baseline is 3; the description nonetheless adds edge-case semantics the schema omits, namely that a non-numeric max_price_usd or limit returns an error and that no match yields count 0 with empty results. It does not add syntax guidance beyond the schema examples.

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?

Names a specific verb+resource ('Browse or keyword-search the verified catalog of pay-per-call (x402) agent services') and explicitly distinguishes itself from the siblings lookup and get_service by the condition that selects each. 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?

States exactly when to use it ('when you don't know the task name or want to see what exists') and names the two alternatives with their own selection conditions ('lookup to rank endpoints for a known task at a max price, and get_service for one id's full record'). Nothing is left to inference.

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