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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds context about what is returned (body_text, body_html) and specific use cases (SMTP response, gate denial reason), which are behavioral details beyond the annotations. No contradictions.

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 sentences: first states purpose, second provides use-case examples. No wasted words, front-loaded with key information. Excellent conciseness for the complexity 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?

Given the tool's simplicity (1 parameter, 100% schema coverage, good annotations, and an output schema), the description is complete. It explains what the tool does, what fields are included, and when to use it. No gaps remain.

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% with a single parameter 'id' described as 'Sent email ID from listSentEmails or a /send-mail response.' The tool description does not add additional parameter semantics beyond what the schema already provides, so baseline 3 is appropriate.

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 clearly states the action: 'Get the full record for a single sent email by id, including body_text and body_html.' It uses a specific verb and resource, and the sibling list includes similar tools like getEmail and listSentEmails, but this description uniquely specifies that it retrieves the full record for a sent email, differentiating it from others.

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 provides explicit use cases: 'Use to inspect delivery details for a specific send — e.g. the SMTP response on a bounced row, or the gate denial reason on a gate_denied row.' This tells the agent when to use the tool. However, it does not mention when not to use it or offer direct alternatives, though the sibling names imply alternatives like listSentEmails.

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