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

With no annotations, the description fully carries the behavioral disclosure burden, and it does so thoroughly. It explains the x402 PaymentRequired flow, that nothing executes or is charged until payment verifies, and that a zero-result scan is still a billable completed run rather than an error.

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 well-structured with WHEN, NOT for, and Returns sections, and the key usage conditions are front-loaded. It is dense but every clause earns its place, though the phrasing 'the user wants names that match it now' is slightly awkward and the payment detail is lengthy.

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 two-parameter tool with no output schema and no annotations, the description covers return shape, payment behavior, and key error semantics, which is quite complete. It could additionally point the agent to siblings for discovering capability ids or retrieving input schemas, but the sibling list already signals where to look.

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 schema already documents both parameters at 100% coverage: id is the capability id and input is an object conforming to the capability's input_schema. The description adds no additional parameter-level meaning, but the baseline of 3 applies because the schema covers the needed semantics.

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 indicates this tool runs a selected listed skill/capability to produce matching names, and it explicitly excludes quotes, news, and unlisted setups. It does not state the core action in a single direct 'invoke this capability to return names' sentence, but the WHEN guidance makes the purpose sufficiently clear.

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 gives explicit WHEN conditions — chosen skill, user wants names now, ready to pay — and explicit NOT-for exclusions such as quotes, news, and unsupported patterns. It does not name sibling alternatives like search_capabilities or get_capability for finding a listed capability, but the usage context is otherwise clear.

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