mail_read_attachment

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

Discloses return format (base64), size bound, rejection behavior, and safety guarantees. This goes beyond the readOnly/destructive annotations by detailing specific limits and side-effect-free behavior.

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 concise sentences with no redundancy. The main action is front-loaded, and additional constraints are presented efficiently.

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?

The description is sufficient for a simple read tool: it states the action, output format, size limit, and safety behavior. No missing information is needed for correct invocation.

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 covers all parameters with patterns, formats, and constraints, so baseline is 3. The description adds minimal parameter-specific detail (e.g., size limit relates to maxBytes) but doesn't explain accountId, messageId, or attachmentId beyond what schema already defines.

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?

Clearly states the verb 'Read' and the resource 'file attachment', distinguishing it from sibling tools like mail_list_attachments (list) and mail_read_message (read message). The description makes the tool's purpose unambiguous.

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?

Provides usage constraints: size limit (2 MiB), rejection of item/reference attachments, and safety instructions (no URL follow, no execution, no disk writes). While it doesn't explicitly contrast with alternatives, the context is clear from the sibling list.

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