reply-mail-message

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

The description discloses key behaviors beyond annotations: 'This method saves the message in the Sent Items folder,' and warns about HTTP 400 errors for conflicting parameters. Annotations already indicate destructiveHint=true, and the description adds context about the action's persistence. No contradiction with 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?

The description is front-loaded with the main purpose and provides necessary details in a structured manner using bullet points. While it is somewhat detailed, each sentence contributes useful information. Minor redundancy (e.g., repeating format options) could be trimmed, but overall it is concise for the complexity.

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 complexity (4 parameters, nested input, no output schema), the description covers format options, constraints, and the saving behavior. However, it lacks information about the return value or response format on success/failure. Additionally, it does not guide on when to choose JSON vs MIME format. The missing output schema increases the need for such details.

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 description adds meaning to the 'body' and 'Comment' parameters by specifying that only one should be used, clarifying the rule about replyTo recipients, and explaining base64 encoding for MIME. Schema description coverage is 75%, and the description compensates for missing top-level schema descriptions. However, it does not address the 'includeHeaders' or 'excludeResponse' parameters.

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 tool's purpose: 'Reply to the sender of a message using either JSON or MIME format.' It identifies the action (reply), resource (message), and format options, distinguishing from siblings like 'reply-all-mail-message' and 'create-reply-draft' by name and the explicit mention of replying to the sender only.

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 guidance on when to use the tool, including format choices (JSON vs MIME) and constraints like not specifying both comment and body. It mentions an alternative (creating a draft for later sending) and includes a TIP about using the 'comment' field. However, it lacks explicit guidance on when NOT to use the tool (e.g., when replying to all or when forwarding).

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