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

Annotations already declare destructiveHint=true and idempotentHint=true, so the bar is lower, but the description still adds real value: it discloses optimistic concurrency ('stale state fails unchanged') and the reconciliation requirement after an uncertain result. It does not spell out that unsubscribe_all removes every existing region at once, which is the destructive outcome an agent most needs to understand.

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 dense sentences with no filler, and the action set is front-loaded before preconditions. The final reconciliation clause is somewhat compressed but still earns its place as behavioral guidance.

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?

The tool has an output schema, so return values need not be described, and the description covers the mutation, concurrency, consent, and idempotency dimensions an agent needs to call it safely. The remaining gap is the overlap with the waitlist.unsubscribe sibling and the full destructive scope of unsubscribe_all.

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 0%, so the description carries the full load, and it does well: token provenance ('opaque Manage regions token'), expectedVersion's source, idempotencyKey's stability, consent's requirement, and the three action values are all named. It does not mention that regionKey must come from a fixed four-value enum, nor that regionKey is conditionally required for the add/remove actions.

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 set and scope: 'Add or remove one exact region, or unsubscribe from all updates', which pins down the operation far better than the title's generic 'Change regions'. The 'one exact region' wording also distinguishes this from any bulk-region sibling.

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?

Gives clear operational preconditions: the version must come from waitlist.preferences.get, adding a region requires explicit consent, and stale state must be reconciled after a failed attempt rather than retried blindly. It falls short of a 5 because a sibling tool named waitlist.unsubscribe exists and the description never says when to use that instead of this tool's unsubscribe_all action.

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