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

Annotations already declare the safe read profile (readOnlyHint, idempotentHint, destructiveHint=false), and the description adds real behavioral detail on top: bodies over 25000 characters are truncated and flagged via `bodyTruncated`, and the html fallback behavior is explained. These are non-obvious traits the agent could not learn from the 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?

A single dense sentence with a semicolon and one parenthetical; it is front-loaded with the primary return value and every clause carries information. No filler, though the packed parenthetical slightly reduces scannability.

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 must sketch what comes back, and it does: body as plain text, optional html, and the truncation flag. It stops short of describing the remaining email fields the agent will receive, but covers the parts that vary by request.

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 100%, so the 3 baseline applies, but the description adds genuine semantic value: `includeHtml` is not merely 'also return html' — it explains that html is returned anyway when the email has no text part. That fallback nuance is beyond what the schema states.

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 states a specific resource and scope: 'One email with its body as plain text', which implicitly distinguishes it from the sibling list_emails by returning a single item. The title supplies the verb 'Get'. It is clear, though it never explicitly names an alternative.

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?

There is no when-to-use guidance and no mention of alternatives such as list_emails or reply_to_email. The use case (retrieve a single email by id) is only implied by the resource noun, leaving the agent to infer context.

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