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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds a meaningful behavioral nuance—'Remote acceptance does not prove inbox placement'—which clarifies the semantics of the returned status beyond what annotations provide. This is valuable context for interpreting results.

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 description is two sentences with zero filler. The primary action and resource are front-loaded in the first sentence, and the caveat is placed second, adding essential context without redundancy.

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?

Given the presence of an output schema (return format is covered there), the single parameter is fully documented in the schema, and annotations carry the read-only/idempotent safety profile, the description provides everything needed for correct invocation and interpretation. The caveat about acceptance vs. delivery adds a subtle but important behavioral expectation that completes the picture.

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 input schema fully describes the requestId parameter, including format (uuid) and a clarifying note about it not being an email address or Message-ID. The description does not add any further parameter-level meaning, so the baseline of 3 applies given 100% schema coverage.

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 uses a specific verb ('Get') and names the resource ('per-recipient queue and delivery status for a requestId'), making it clear what the tool returns. The caveat about remote acceptance vs. inbox placement further distinguishes it from send-related siblings like send_email or cancel_send, which focus on the send action rather than status.

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 description implies the tool is used after a send request (requestId originates from send_email), but it does not explicitly state when to use it versus alternatives like get_message for content or cancel_send for cancellation. It lacks explicit exclusions or conditions, leaving the usage context to inference.

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