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

No annotations are present, so the description carries the behavioral burden. It is clearly read-only in nature (

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?

One dense sentence that enumerates the returned statistics and clearly states the tool's scope. No filler, no 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?

No parameters, no annotations, no output schema, but the description lists the key fields returnedholistically and matches the tool name. What's missing? not much; expected return values are literally enumerated.

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?

Tool has 0 parametersais schema coverage 100%? Actually no properties. With zero params, baseline 4. Description compensates by telling agent exactly what the output contains (catalog size, median price, 30-day calls, unique payers, categories). It doesn't need to explain any params.

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 states a clear verb (statistics of market) with a specific subject (x402 service market) and enumerates the concrete metrics returned: catalog size, median price, total 30-day calls, unique payers, and top categories. This distinguishes it from the sibling search_x402_services, which presumably searches individual services rather than aggregating market-level stats.

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 clearly frames this as a market-level statistics endpoint, so an agent can infer when to call it (when aggregate market numbers are needed). However, it never explicitly contrasts it with the sibling search_x402_services or states when *not* to use it, leaving the routing decision to inference.

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