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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new operational context beyond that: it reads a public discovery manifest at /.well-known/x402, needs no credentials, and costs nothing — all of which matter for an agent deciding whether it can call this unauthenticated.

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?

Two tight sentences: the first front-loads the returned content, the second covers cost, auth, and the recommended call ordering. No filler, and the most decision-relevant facts (free, no credentials) come early.

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 already exists, so the description is not obligated to document return values, yet it still summarizes them usefully. Combined with the no-auth/no-cost note and the call-ordering guidance, an agent has everything needed to invoke this correctly.

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 there is no parameter semantics to document and the baseline is 4. The description correctly implies a parameterless discovery call rather than suggesting any input is required.

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 (describe) and resource (the VERIDEX service) and enumerates exactly what the payload contains: price, settlement network/asset, receiving address, and endpoints. This cleanly separates it from the sibling verify_company_by_cif, which performs the actual verification.

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 an explicit trigger: 'Call this before verifying if you need to know what a verification costs or where the payment goes.' That is a clear when-to-use condition tied to the sibling verification flow. It does not state when not to call it or name the alternative tools directly, so it falls just short of a 5.

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