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

Annotations already declare readOnly/no-destructive/closed-world, but the description adds real behavioral context: the signed/HMAC signature condition, the specific field set returned, and the eventual-consistency caveat that a just-issued receipt may not be fetchable yet. That freshness warning is the kind of trait an annotation cannot express.

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?

Front-loaded with the or, and every sentence carries information — provenance, payload, scope boundary, freshness caveat. The mid-sentence field enumeration is long and partially redundant with the output schema, which keeps it from a 5.

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-only lookup with an output schema present, the description covers everything the agent needs: id provenance and format, what the payload contains, the signed-signature condition, and the not-yet-fetchable edge case. Nothing material is missing.

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 id parameter is already fully documented there, so the baseline is 3. The description adds only marginal value by repeating the id shape and noting the value originates from verify_offer's receipt.id.

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+resource combination ('Fetches an evidence receipt by its id') and pins down the id format. It also ties the tool to its issuing sibling ('as issued with a verify_offer result'), so an agent can place it relative to verify_offer 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?

Clear context: use it when you hold a receipt id produced by verify_offer, and the clarifying line 'It holds the citation, not the product's offers' steers an agent away from expecting offer data. It never states an explicit when-not or names a competing lookup tool, so it falls short of a 5.

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