Create Draft

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

Discloses core behavior: draft is not sent, saved, and can be sent later. No annotations provided, so description carries burden. However, lacks details on side effects like overwriting existing drafts. Still, essential behavior is covered.

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 paragraphs, front-loaded with purpose and usage. Every sentence adds value without redundancy. Well-structured for quick understanding.

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?

Covers main scenarios (new/reply), parameter usage, and outcome (draft saved). Lacks return value description, but given good schema coverage and no output schema, it is fairly complete.

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 coverage is 100% with descriptions, but the description adds value: explains usage of conversation and from_field for replies vs new messages, mentions HTML support for body, and adds total payload max 10MB beyond schema's maxItems.

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 'Creates a draft message that is NOT sent,' specifying the exact verb and resource. It distinguishes this tool from sending actions and manages both reply and new message scenarios.

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?

Explicitly states when to use: 'Use this when the user wants to compose a message and review it before sending.' Provides guidance on using conversation ID for replies vs omitting for new messages, and mentions send_message as alternative.

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