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

Annotations already declare non-read-only, non-destructive, non-idempotent, closed-world. The description adds genuinely new behaviour: the receipt returns to an 'unmatched' state, that state is visible, and the reason is retained on the record — telling the agent the action is auditable and effectively reversible. It does not say what happens to the previous match record or whether repeating the call errors, despite idempotentHint=false.

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 action is front-loaded in the first clause, which is good. However 'A match was a reasoned act; undoing it is one too' is atmosphere rather than instruction, and 'The receipt goes back to unmatched, a visible state' duplicates the trailing 'Effects: receipt unmatched.'

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 two-required-parameter mutation with annotations and no output schema, the description covers trigger, effect on state, and audit consequence. An agent has enough to invoke it correctly and choose it over purch_match_receipt.

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%, but the schema text is bare ('Why.', 'The receipt.'). The description adds that the reason is persisted on the record and that receipt_id refers to a receipt currently attached to a transaction. That is useful but thin; baseline 3 applies since the schema nominally documents both parameters.

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: 'Detach a receipt from its transaction, with a reason.' It also names the implied counterpart ('then match again'), which lets an agent separate it from purch_match_receipt. It does not explicitly name the sibling tool, so it stops short of 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?

'Use it when the person says the receipt belongs to a different row or card — then match again' gives a concrete triggering condition and the follow-up action. There is no explicit when-not or prerequisite/permission guidance, so it is clear context rather than full routing guidance.

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