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

Annotations already carry destructiveHint=true, so the description's added value is the billing note ('No additional charge or new payment'), the revocation semantics, and the explicit statement that it does not read messages or extract codes. These are real disclosures beyond the annotation set, though authorization/permission requirements and what happens to already-fetched codes are not covered.

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?

Front-loaded with the action and the effect, then usage trigger, then sourcing of parameters. A few sentences are near-redundant — the destructive warning restates what annotations already flag, and 'no additional charge or new payment' doubles up — but nothing is filler at the paragraph level.

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 destructive, credential-based delete with an output schema present, the description covers what is removed, where the credentials come from, the cost implication, and the ordering constraint relative to message retrieval. Remaining gaps (permission scope, post-delete state, error cases) are modest.

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 only 33%, with only access_token documented in the schema; the description compensates by stating that inbox_id, capability and access_token all come from create_email_inbox, which is the key provenance an agent needs. It still does not explain the format/pattern constraints on inbox_id and capability, but the gap is largely closed.

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 ('Delete your existing inbox and revoke access to its mailbox content'), and the effect on mailbox access differentiates it from create_email_inbox, get_email_code and list_email_messages. An agent can pick it out of the sibling list 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?

'Use after testing is complete' gives a clear trigger condition, and 'read needed messages before deleting' tells the agent what it must do first. It does not explicitly name alternatives (e.g. list_email_messages) or state when deletion should NOT be attempted, so it falls 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.