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

Beyond the annotations (readOnlyHint, destructiveHint=false, openWorldHint=false), the description adds pricing ($0.003 via x402), a concrete rate limit (10 free searches per IP per day), and the fact that sponsored listings arrive in a separate list. Those are exactly the operational details an agent cannot infer from structured fields.

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 tight sentences, front-loaded with what is searched, then results shape, then the alternative tool, then cost/quota. No redundancy with the title or schema.

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?

No output schema exists, and the description compensates by describing the return shape: listings ranked by relevance, trust score and usage, each carrying price, live status and invocation info, with sponsored results split out. Combined with the quota and cost notes, an agent has everything needed to call and interpret the result.

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 each of the 5 parameters (kind, limit, query, network, max_price_usd) is already documented in the schema, including the enum meaning. The description only alludes to price and status filtering, adding no syntax or format detail beyond the schema, so the baseline 3 applies.

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 (search) and resource (vetted, live-monitored x402 APIs and MCP servers), and immediately contrasts itself with recommend_service for single picks. An agent can distinguish it from siblings like get_service or list_categories without opening a 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?

Explicitly routes to recommend_service when the agent wants one pick for a task, and discloses the per-IP free quota and per-call cost, which tells the agent when calling is cheap. It stops short of stating when-not to search at all (e.g. if the agent already knows the service id), so it is not a full 5.

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