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

The annotations already establish read-only, idempotent, open-world, and non-destructive behavior. The description adds useful context beyond annotations by stating that results are live-probed resources with a measured 402 Score and that the tool is free, which provides operational expectations without contradicting the annotation profile.

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?

The description is three short sentences with the primary purpose front-loaded. 'Free.' is a concise, relevant cost signal, and every sentence adds distinct information without filler or redundancy.

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 two-parameter read-only search tool, the description covers the search target, result characteristics, and cost well. It does not detail the exact return structure or pagination behavior, but the 'measured 402 Score' hint gives agents a reasonable expectation of result contents. Given the absence of an output schema, slightly more explicit return formatting would be useful but is not critical.

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 description coverage is 100%, so the baseline is 3. The description reinforces the `q` parameter with the same capability examples already present in the schema, but adds no new meaning about `limit`, parameter formatting, or result constraints. It therefore does not exceed the baseline.

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 clearly identifies a specific verb ('Search') and resource ('Market402 verified index of the whole x402 economy'), and scopes the query by 'capability' with examples. It also conveys the result nature ('real, probed resource with a measured 402 Score'), which helps distinguish it from catalog-style siblings, though it does not name any sibling explicitly.

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 description gives clear context for when to use this tool: searching for services by capability keyword like 'ocr' or 'market-data'. However, it does not mention alternatives or conditions where a sibling such as get_catalog or get_sample would be more appropriate, leaving the 'vs alternatives' aspect unaddressed.

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