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

Far beyond the destructiveHint=true annotation: the description states messages are destroyed with the inbox, the local part is never reissued, later mail is dropped rather than bounced, and there is no refund or undo. It also discloses the auth model (ownership proved by the paying wallet via signed message on the domain's own route) and the refusal payload that reveals details.expected, including both EIP-191 and ed25519 signature forms.

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 core action and its consequences are front-loaded and efficient. The final third pivots to a generic feedback-channel pitch ('Complaints, questions, quote requests... every report is read and analysed daily') that reads as boilerplate shared across tools rather than being specific to releasing an inbox, lengthening the description without helping selection.

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 an irreversible mutation with no output schema, the description covers consequences, the signing/ownership requirement, and the recovery path when a signature is refused. It does not address edge cases such as releasing an already-expired inbox or timing relative to expiry, but the agent has enough to invoke it correctly.

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%, so the baseline is 3, but the description genuinely enriches the signature parameter by explaining the refusal/retry flow and the exact two signature encodings accepted. It also adds the authorization context (must be the paying wallet, no account) that the schema cannot express. nonce and signedAt semantics are left entirely to the schema, which already documents them.

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?

Opening sentence gives a specific verb and resource: 'give up an inbox you own before it expires', with the irreversible consequence spelled out. An agent can distinguish it from create_inbox, read_inbox, or claim_release at a glance. It could be sharper about the distinction from the similarly-named free_inbox and claim_release siblings, which it never mentions.

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?

'before it expires' and 'There is no refund and no undo' imply the release-vs-let-expire decision, and the ownership-proof flow is described. However, it never states explicitly when to call this versus free_inbox or claim_release, nor what happens if the inbox is already expired. Usage is inferable but not spelled out.

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