x402 catalog statistics

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint, so the safety profile is covered. The description still adds value by stating it is free, takes no parameters, returns aggregate-only data, and exposes the specific verdict categories returned. It stops short of describing pagination or freshness guarantees, which keeps it off a 5.

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?

Well front-loaded: purpose first, then usage, then scope exclusions and alternatives. The 'Read-only, free, no parameters' tail slightly repeats the readOnlyHint annotation and the empty schema, but it is short and mildly useful.

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?

With no parameters, no output schema, and annotations covering the safety profile, the description supplies everything needed: what is measured, the categorical breakdown, and explicit sibling routing. No relevant gap remains for an agent deciding whether to call it.

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?

The tool takes zero parameters, so the baseline is 4. The description confirms 'no parameters' and instead uses the space to describe the output shape (verdict buckets, last-computed time), which is the useful information here.

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 and resource ('Get an overview of the whole monitored x402 catalog') and enumerates exactly what is returned: endpoint counts, per-verdict breakdowns, and last-computed timestamps. It explicitly positions itself against siblings ('It says nothing about any single endpoint'), so an agent can distinguish it without opening another 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 names when to use it ('for context or reporting') and routes to the correct alternatives with the selecting condition: check_endpoint for one endpoint, top_endpoints for a ranked list, check_payment before paying. Nothing is left to inference.

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