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

With no annotations, the description carries the full burden and does disclose meaningful traits: the receipt is stored, cryptographically signed with Ed25519, immutable evidence of a past decision, and free of charge (no metering/cost concern). It does not cover failure behavior (unknown/expired receipt_id, authorization needed to read a receipt), which is the main remaining gap for an annotation-free tool.

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 sentences, front-loaded with verb/resource/key and followed by the payload contents and the routing disambiguation. Every clause carries information (signature scheme, returned fields, cost, sibling exclusion) with no filler.

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 single-parameter read tool with no output schema, the description usefully enumerates the returned fields and states cost and signature type, which is exactly what the missing output schema would otherwise need to supply. Only error/absence handling is unaddressed, a minor gap.

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 100% and the single parameter's schema already documents the 'rcpt_... from verify_business' format and origin. The description only restates that lookup is by receipt_id, adding no syntax, format, or validation detail beyond the schema, 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?

States a specific verb (Retrieve) plus the resource (a stored, Ed25519-signed verification receipt) and the lookup key (receipt_id), then enumerates the payload (inputs, decision, reasons, fact ids, value hashes, rules version, time). The clause 'not a check' explicitly separates it from the sibling verify_business, so an agent can route without opening either 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?

'Use it to prove what was checked before an action' gives a clear use context, and 'not a check' rules out the obvious wrong use (treating it as a verification call). It stops short of a full when-to-use/when-not statement (e.g., whether receipts expire or when no receipt exists), so it lands at 4 rather than 5.

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