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

No annotations are provided, so the description carries the full burden and does so: asynchronous issuance, `status: pending` with a retry delay, the distinction between `receipt_pending` and `checkout_in_progress`, and the credential-scoping rule ('Only the credential that made the purchase can read its receipt'). It even warns that a receipt attests the call, not settlement, with `settlement: not_attested` semantics.

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?

Purpose and the prefer-the-card routing rule are front-loaded, and every sentence carries actionable content (status codes, auth, settlement caveat). It is dense and long, but not padded; a slightly tighter grouping of the status-code discussion would improve it.

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?

Despite an output schema existing, the description still frames the payload (receipt id, JWS signature, verification, settlement flag) and covers the async/error paths and auth constraint. For a trust-attestation read tool, an agent has everything needed to call it correctly and interpret the result.

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% and both parameters are documented in the schema (including agent_key's sandbox-credential fallback meaning). The description adds no per-parameter syntax or format detail beyond that, so the baseline of 3 applies.

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?

Opens with a specific verb and resource: 'Retrieve the signed trust receipt for a checkout.' It clarifies scope (records the complete_checkout call) and distinguishes itself from get_store_trust and the checkout-completion siblings. An agent can identify the tool 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?

Explicit when/when-not guidance: prefer the interactive cart card, only call when there is no card or the buyer asks later in a new turn. It also states the precondition (read `order_placed` before claiming a purchase) and points to the checkout guide resource, leaving nothing to inference.

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