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

Annotations already declare readOnly, idempotent, non-destructive, non-open-world behavior, so the safety profile is covered. The description adds genuinely useful non-obvious behavior: Amazon's delivery callback lags by seconds to minutes, so a stale "sent" is expected. It does not cover auth requirements or error behavior for unknown ids.

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: the first defines the resource and return values, the second supplies the timing caveat. No filler, and the core purpose is front-loaded.

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, read-only tool with no output schema, the description usefully enumerates the status values and timing behavior. It is nearly complete; only error/unknown-id behavior is unaddressed, which is minor.

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 id parameter, so the description must carry the burden. It implies the id identifies an email previously sent via send_email but never explicitly states that the parameter is the message identifier returned by that call, leaving a small inference gap.

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 gives a specific verb+resource (status of an email sent via send_email) and enumerates the possible outcomes (sent, delivered, bounced, complained), immediately disambiguating the generic name get_email from sibling tools like send_email.

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 clearly situates the tool in a workflow — call it after send_email to check delivery outcome — and pre-empts a common misuse (treating an immediate "sent" status as a problem). It stops short of stating explicit exclusions or naming alternative siblings.

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