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

With no annotations provided, the description carries the full transparency burden. It discloses the ranking criteria (proven-accurate sellers first, then payment-safety, then price), the market coverage (every reachable endpoint), and that results are pre-vetted. It also hints at the read-only nature ('Searches'). While it doesn't detail error handling or limitations, the disclosed behavior is substantive and helpful, meriting a 4.

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 about 70 words but every sentence is purposeful. It is front-loaded with an explicit usage trigger, then explains what the tool does, its coverage, and the recommended next step. There is no redundancy or filler, and the structure guides an agent quickly. This is an efficient, well-organized description.

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?

Given the tool's complexity (4 parameters, no output schema, no annotations), the description provides a solid foundation: it explains when to use it, what it returns (ranked shortlist), the ranking logic, and the follow-up action. It omits explicit details on return format (e.g., exact fields) and edge cases (e.g., no results), but these are not critical for an agent to invoke the tool correctly. The description is adequate and complete enough for the context.

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%, meaning all four parameters (task, limit, max_price_usdc, min_reliability) already have detailed descriptions in the schema. The tool description does not add any extra semantic meaning beyond the schema—it does not explain parameter relationships, constraints, or usage nuances. Per the calibration, this warrants a baseline 3.

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 states a specific verb-resource combination: searches the x402 market for APIs matching a described task and returns a ranked shortlist. It differentiates itself from siblings by explicitly noting it covers every reachable endpoint, not just ones previously used, and names check_before_paying as a distinct next step. The purpose is unambiguous and well-scoped.

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 opens with 'USE WHEN you need an API that does something and want payable options,' providing a clear trigger condition. It also gives workflow guidance (next step: check_before_paying) and notes it covers more than just previously bought endpoints, implicitly contrasting with other tools. However, it doesn't explicitly state when not to use this tool or name specific alternatives for exclusion, so it falls short of a 5.

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