Proof that a digital deliverable arrived and matched what was promised (PAID $0.10)

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

Annotations already disclose non-readonly, non-idempotent, open-world, non-destructive behavior; the description adds genuinely new context in the form of a concrete price (0.10 USD, USDC on eip155:8453/base via x402), which tells the agent this is a paid call with a specific payment rail. It does not say what the call actually creates, whether a repeat call duplicates a record (relevant given idempotentHint=false), or what preconditions exist, so it adds value but leaves the key mutation traits implicit.

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 short lines with the purpose front-loaded and the payment route second; nothing is padded. It is slightly redundant in restating the title verbatim, and the route line is metadata rather than guidance, but the text is tight overall.

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?

This is a non-idempotent, paid, open-world mutation tool with six parameters at low schema coverage and a nested deliverable object. An output schema exists so return values needn't be described, but the description omits the attestation outcome semantics, payment/authorization requirements, and parameter meaning, leaving too much for the agent to infer.

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 only 17% across six parameters including a nested _A2ADeliverable object, so the description must compensate and largely does not — recipient, delivered_at, acknowledged_at/by and promised_sha256 are never explained. The only hint is the phrase 'matched what was promised', which weakly implies promised_sha256 is compared against deliverable.sha256, but no comparison or format semantics are spelled out.

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 phrase 'Proof that a digital deliverable arrived and matched what was promised' identifies the resource and the attesting action, so an agent can roughly tell it apart from attest siblings like v1_readiness_attest or v1_uptime_attest. However it is a noun phrase rather than a verb+resource statement, and it never explicitly contrasts itself with the many other attest/receipt tools in the sibling list.

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 states the price and the POST route but gives no when-to-use conditions, no prerequisites, and no mention of alternatives such as v1_receipts_mint, v1_output_verify, or v1_task_acceptance, all of which overlap with 'proving a deliverable arrived'. The only selection signal offered is the $0.10 cost.

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