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

Annotations declare readOnlyHint=false and openWorldHint=true, but the description adds genuinely useful behavioral detail: no destination is contacted, no acknowledgment obtained, nothing delivered or persisted, and no execution authority is created. It also notes that payment access records are durable, which explains the non-read-only annotation. This is real context beyond structured fields.

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 text is highly repetitive, restating the no-authority/no-delivery boundary three or four times ('creates no execution authority', 'grants no authority', 'never supplies server credentials'). Payment terms lead the description while the actual purpose trails, so it is not front-loaded around what an agent needs.

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 four-parameter, 0%-coverage tool with no output schema and nested union types, the description should carry the full explanatory load. It supplies rich boundary/behavioral framing but leaves parameters and expected output entirely unexplained, so an agent still cannot construct a correct call from the description alone.

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% across four required parameters, so the schema documents none of them semantically. The description alludes loosely to 'source/destination binding' and 'caller-supplied data', but never explains the mode constant, the agent/callback destination kinds, the receipt/passport/proof reference kinds, or payload_sha256. It does not compensate for the coverage gap.

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 operative sentence 'Prepare a reference envelope and deterministic source/destination binding digest' names a specific verb and resource, but it is buried under dense payment and legal boilerplate. It never distinguishes itself from close siblings like wever_proof-inbox or wever_receipt-passport, so an agent cannot route confidently between them.

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 covers pricing/access (x402 Base USDC or free tier) but gives no guidance on when to choose this tool over its many siblings, nor any exclusions. Usage is only implied through the 'prepare_proof_relay' framing.

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