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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=true), and the description adds material context beyond them: a real per-call cost (0.002 USDC via x402), retry semantics that require re-sending the same idempotencyKey and payment authorization, and an explicit epistemic caveat that signed declarations do not independently prove execution. It does not describe persistence failure modes or what the stored receipt looks like.

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?

Four short sentences with zero filler; the purpose is front-loaded and each subsequent sentence (price, retry rule, disclaimer) adds a distinct fact 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?

An output schema exists, so return values need not be explained, and the description covers cost, idempotency, and the trust caveat. What is missing is guidance on the relationship to the sibling prepare/verify tools, which matters for a tool in a multi-step receipt flow.

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% with two parameters, one of which is a deeply nested required event object, so the description carries the burden. It names both parameters and gives genuine semantic value for idempotencyKey (retry preservation), but says nothing about the meaning of the event fields or what a well-formed declaration contains.

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: 'Persist a signed execution declaration receipt.' An agent can tell this tool writes a receipt, but the description never differentiates it from the siblings prepare_agent_event and verify_agent_receipt, so the boundary between issuing and verifying is left to inference.

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?

Usage is only implied. 'Preserve event, idempotencyKey and payment authorization on retries' is a useful operational instruction, but the description never says when to call this tool versus prepare_agent_event or verify_agent_receipt, nor does it state any prerequisite (e.g. that a receipt must be prepared first).

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