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

Annotations only supply generic hints (readOnlyHint=false, destructiveHint=false, idempotentHint=false); the description goes well beyond them by disclosing that the call is non-mutating, returns a preview of what would change plus a confirmation link, and that only the merchant on that page can execute the deletion. That explains the otherwise puzzling destructiveHint=false and tells the agent what the return contains in the absence of an output schema. There is mild semantic tension between "changes nothing" and readOnlyHint=false, but it reflects a deferred-confirmation mutation rather than a false claim.

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 purpose and the critical non-mutation/confirmation behavior are front-loaded and earned. But the sentence "Money is integer minor units (cents)" is irrelevant boilerplate for a tool whose only parameter is a popup id or name, so one of four sentences is pure noise.

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 one-parameter tool with no output schema, the description covers what the call does, what it returns (preview and confirmation link), and who finalizes the action — enough for correct invocation. Residual gaps are minor: nothing about confirmation-link expiry or what the preview enumerates.

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 is well documented ("The popup's id or name, as popups.list gives them"), so the schema carries the burden. The description adds no syntax or format detail beyond that, making the baseline 3 correct.

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?

"Delete a popup" gives a specific verb and resource, and it is trivially distinguishable from siblings popups_list and popups_set. It is slightly muddied by the later claim that calling it "changes nothing," which makes the agent wonder whether the tool deletes or only previews a deletion.

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?

The description conveys the real workflow constraint — the call only stages a change and only the merchant, on the returned page, can complete it — which is genuine usage context an agent needs. However, it gives no explicit when-to-use/when-not, no reference to popups_list for obtaining the id, and no comparison against alternatives like popups_set.

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