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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description adds context annotations cannot carry: the mail bypasses Trash entirely, the deletion is permanent, and the address is retired so it cannot be recreated. This tells the agent the blast radius is broader than a single message and that the operation is irreversible — exactly what a destructive tool needs.

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?

One sentence, front-loaded with the destructive action, followed by the two highest-value caveats (no Trash, address retired). Nothing is padded and nothing important is buried.

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 mutation tool with an output schema, the description covers everything the agent needs: irreversibility, scope, non-recoverability, and a human-confirmation prerequisite. Return values are handled by the output schema and correctly omitted here.

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?

The single inbox_id parameter has 0% description coverage, but the schema self-documents via format: uuid plus a strict UUID regex, so syntax meaning is not really missing. The description's reference to "the exact address" describes a human confirmation step rather than the inbox_id argument itself and does not clarify that the identifier is a UUID, so it adds only marginal semantic value.

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 ("permanently delete an inbox") and immediately differentiates scope from the sibling delete_message / delete_thread / delete_draft tools by adding "and all its mail." An agent can tell what this destroys without opening any schema.

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 an explicit precondition — confirm the exact address and full scope with the human — which is unusually strong guidance for a destructive tool. It does not, however, name an alternative (e.g., update_inbox or restore_message) or state a when-not-to-use condition, so it stops short of a 5.

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