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

No annotations are provided, so the description must convey behavioral traits itself. It discloses that the tool is free, returns paginated results, and applies wash-filtering using the same algorithm as paid endpoints. It also describes the output composition (stats and label mix). It does not mention read-only status or rate limits, but for a search tool this is sufficient. It adds meaningful context beyond what the schema provides.

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 front-loaded with the core action and contains several useful details (free tier, pagination, wash-filtering, use case). There is a minor redundancy: 'Free tier. No payment required.' conveys the same information in two phrases, which is a small efficiency lapse. Overall it is concise and well-structured for its length.

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?

The description covers the tool's purpose, output type, filtering capabilities, and key behavioral attributes (free, wash-filtered, paginated). Since an output schema exists, return values do not need to be detailed. It omits explicit mention of read-only behavior or default behavior with no filters, but these are reasonably implied. For a 6-parameter search tool with no annotations, the description is highly complete.

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 adds high-level use context (e.g., 'topic, chain, or seller wallet') but does not add specific parameter syntax or format details beyond the schema. It slightly reinforces the purpose of the 'search' and 'chain' parameters but does not go beyond the schema's own descriptions, so the baseline is appropriate.

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 uses a specific verb ('Search') and a clear resource ('the index of 36k+ x402 services') with filters, and it states the return type (paginated list with stats and label mix). It distinguishes itself from sibling tools like x402_get_service (single service), x402_get_categories, and x402_get_trends by focusing on search/filter over the whole index.

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?

Provides explicit use context: 'Use this to find services by topic, chain, or seller wallet.' It does not explicitly name alternatives or when-not-to-use, but the sibling tool names and the stated purpose make the differentiation clear. This is solid guidance without exclusions, qualifying as 'clear context, no exclusions.'

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