Verify a Spanish company by CIF

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

Goes well beyond the annotations by disclosing the full x402 payment handshake, the exact payment_required envelope shape, which errors are free (not_found, source_unavailable) vs billable, and retry semantics per error code. This is behavior an agent could not infer from readOnlyHint/openWorldHint alone.

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?

Front-loaded with purpose and deliverable, then a dedicated payment paragraph and a typed-error paragraph. Dense and useful with no filler, though the payment guidance is slightly verbose relative to what an agent needs on the first read.

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?

An output schema exists, so return values need not be explained, and the description nonetheless previews them. Payment, error taxonomy, and retry policy are all covered; only the idempotency_key parameter is left unexplained, a minor gap for an otherwise complete definition.

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 0%, so the description carries the full burden. It explains x_payment thoroughly (base64 payload from a settled challenge) and cif is self-evident, but idempotency_key is never mentioned anywhere, leaving one of three parameters undocumented.

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 (verify) and resource (Spanish company by CIF) and enumerates the returned payload: registry data, BORME status, recent acts, and an explainable 0-100 risk score. This is unmistakably distinct from siblings get_veridex_info and health_check.

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?

Gives explicit operational context: first call returns payment_required, settle and re-call with x_payment, and a clear when-not rule ('Do not retry a 402 without changing the payment'). It also scopes retryability per error code. No comparison to siblings, but they are unrelated utility endpoints, so nothing essential is missing.

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