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

The description adds meaningful behavior beyond the readOnlyHint and openWorldHint annotations: no funds move, it returns the same answer as POST /verify, and it consumes the same per-IP allowance. It does not detail failure modes or full return shape, but the safety and rate-limit context are valuable.

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, front-loaded with the core action and checks. Every sentence adds useful information with no wasted wording.

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 read-only verification tool with full schema coverage and annotations, the description covers the core action, safety, equivalence, and rate-limit impact. It leaves return-value shape and failure behavior somewhat implicit by relying on external POST /verify reference.

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 schema already documents the three parameters and their nested objects. The description adds conceptual context about what is checked but does not add parameter-level meaning beyond the schema.

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 specific verb and resource: 'Check a signed x402 payment against its requirements,' and enumerates the checks performed. This clearly distinguishes it from siblings like get_health, get_config, and payment_status.

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?

It gives clear context for use, including that it moves no funds and is equivalent to POST /verify. However, it does not explicitly contrast with sibling tools such as payment_status or state when not to use it.

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