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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond that: it recomputes a hash chain plus HMAC, `valid` collapses chain-match and server-signature checks, `valid` is false specifically when a row was altered, and `valid` says nothing about approval. That is substantive disclosure for a tool with no output schema.

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 integrity semantics and the `valid` / `approver_confirmation` split are front-loaded in the opening sentences, and the endpoint mapping is a useful trailing anchor. There is mild redundancy in restating falsity twice ('valid is false when a row was altered' after 'valid is true when…'), but nothing wasteful overall.

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?

With no output schema, the description must carry the return semantics, and it does: it defines `valid` and all three `approver_confirmation` values. It doesn't cover what a hash-chain mismatch looks like in the response shape or any error behavior for an unknown receipt id, leaving a small gap for a single-parameter integrity tool.

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 the single `receipt_id` parameter is documented as the public rcpt_… id in the schema itself. The description adds no format, sourcing, or failure-mode guidance for that id (e.g. what happens on an unknown id), 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?

The description names a specific action (recompute the receipt hash chain and HMAC signature) against a specific resource (a stored receipt), and defines what the resulting `valid` flag means, which makes the integrity-check intent distinguishable from retrieval siblings such as get_receipt. It stops short of explicitly contrasting itself with those siblings, so a 4 rather than a 5.

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 implied by the semantics of `valid` (use it to check a record hasn't been altered), and the description explicitly bounds scope with 'valid does not confirm who approved', pointing the agent toward `approver_confirmation` for that question. There is no explicit when-to-use guidance relative to get_receipt or record_approval, and no stated preconditions, so it stays at minimum-viable.

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