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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, non-destructive, closed-world), but the description adds genuinely useful context beyond them: the call requires an existing inbox's agent key as a Bearer credential, and this server cannot create an inbox. That prerequisite is not derivable from the schema or annotations.

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 tight sentences with the operation and the auth prerequisite front-loaded; nothing is wasted. The ambiguous 'the same' phrasing is the only small blemish.

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?

With no output schema, the description should ideally say what a status result contains or what states are possible, which it does not. It does cover prerequisites (existing inbox, agent key) well, so it is adequate but leaves the return side unspecified.

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% for the single required parameter, so the description carries the burden. It does add meaning by identifying operationId as a 'durable operation ID' tied to a send, but gives no format guidance beyond the regex pattern already in the schema.

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 clear verb+resource (look up send status for a durable operation ID) and implicitly distinguishes itself from voidmail_send_once by noting it does so 'without dispatching mail.' However, 'the same durable operation ID' is left slightly dangling — the description never states what it is the same as, which weakens the standalone read.

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?

The phrase 'without dispatching mail' implies this is the non-sending counterpart to voidmail_send_once, so usage is inferable but never stated as explicit when-to-use guidance. No named alternative or condition is given, leaving the routing to inference.

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