send-mail

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

Annotations already indicate destructiveHint=true. The description adds that MIME format saves the message in Sent Items, and JSON allows inline attachments. This provides useful behavioral context beyond 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?

The description is concise, with two paragraphs and a tip. It front-loads the main action and avoids unnecessary detail.

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 complexity (nested objects, 3 params, no output schema), the description lacks details on return values, error scenarios, and the SaveToSentItems parameter. It adequately covers the basic send action but has gaps.

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 67%, so baseline is 3. The description mentions JSON/MIME formats and attachment inclusion, adding some context, but does not explain individual parameters like includeHeaders or excludeResponse, nor the nested SaveToSentItems field.

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 sends a message specified in the request body, using JSON or MIME format. It distinguishes from draft creation by mentioning that alternative, but does not explicitly differentiate from the sibling send-draft-message tool.

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 a critical tip to use list-users for email addresses, and hints at draft creation as an alternative. However, it does not clearly state when to use this tool versus send-draft-message or other mail-related tools.

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