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

Goes well beyond the annotations: discloses the two-phase 402 handshake, that the first call returns isError=true with structuredContent, that settlement auto-confirms with no human approval, and that the response carries _meta["x402/payment-response"]. These are exactly the behavioral traits (protocol, settlement, side effects) an agent needs and that readOnlyHint=false / openWorldHint=true alone do not convey.

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-loads the action and precondition, then walks through the payment flow in a tight sequence. Four dense sentences with no filler, though the protocol details are somewhat crammed together and could be marginally easier to scan.

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?

Given there is no output schema, the description compensates by explaining the error payload and the _meta payment-response on success. The payment protocol, precondition, retry mechanics and confirmation outcome are all covered, leaving nothing essential for a correct invocation.

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 coverage is 100% so id and token are already documented (baseline 3). The description adds the non-obvious second-phase parameter params._meta["x402/payment"] carrying the signed PaymentPayload, which is absent from the declared schema and materially changes how the call is made.

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 (pays a quoted custom request) plus the governing precondition (status = "cotizada"), which cleanly separates it from siblings like cotizar and consultar_estado. An agent can identify exactly what this tool does without opening the 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?

Gives explicit procedural guidance: only call once the request is 'cotizada', call once without payment to get PaymentRequired, then retry the SAME call with the signed payload. It stops short of naming sibling alternatives for the pre-quote or verification steps, but the when-to-use condition is unambiguous.

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