forward-mail-message

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

Annotations already indicate destructiveHint=true. The description adds valuable behavioral context: parameter validation rules (HTTP 400 errors for conflicting specs), the fact that it saves to Sent Items, and the tip to not reconstruct manually. This enriches understanding beyond the annotation flags.

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 well-structured with bullet points for JSON and MIME formats, and a tip. It is front-loaded with the core action. While somewhat lengthy, each sentence adds value and the structure aids readability.

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 no output schema, the description covers side effects (saving to Sent Items), error conditions (HTTP 400), and format choices. It lacks mention of return value or permissions, but is complete enough for a forwarding tool.

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?

With 75% schema description coverage, the description goes further by explaining constraints like the mutual exclusivity of comment and body in message, and the requirement for toRecipients in either the body or parameter. This adds clarity beyond the raw schema.

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 it forwards a message using JSON or MIME format. It distinguishes itself from 'create-forward-draft' by implying immediate sending (saves in Sent Items immediately) and the tip reinforces server-side handling, which sets it apart from manual construction or draft-based workflows.

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 explicitly mentions an alternative: 'Alternatively, create a draft to forward a message, and send it later.' This guides the user to use 'create-forward-draft' when they want to queue a draft. However, it does not explicitly contrast with reply tools or general send, leaving some ambiguity.

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