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

Annotations already declare non-readonly, idempotent and non-destructive, so the main added value is 'Sends nothing' and the Done-button analogy, which clarify there is no outbound side effect. The description does not say whether the clear is reversible, whether the item disappears from list_inbox permanently, or what permissions are needed.

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 compact sentences that lead with the action and then qualify it with the Done-button analogy; no wasted clauses. The analogy, while useful, is slightly informal but earns its place by fixing expectations.

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, no-output-schema tool this covers what an agent needs: what it acts on, where the id comes from, and that nothing is sent. Only the post-clear state (reversibility, inbox effect) is left implicit.

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 parameter is already documented as 'The message id from list_inbox.' The description corroborates that linkage via needs_you but adds no format or edge-case guidance beyond the schema, so the baseline 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 verb and resource ('Clears one message') and scopes it to the automation's needs_you items surfaced by list_inbox, which separates it from siblings like send_reply or approve_reply_draft. It stops short of stating unambiguously whether 'clears' means removal or just state change, leaving a sliver of doubt.

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?

It gives a clear trigger: use this 'once they dealt with it themself', tying usage to human follow-up rather than automation. The closing 'Sends nothing' implicitly tells the agent not to reach for it when an outbound reply is needed, though no sibling is named explicitly.

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