mail_prepare_draft

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

Annotations already mark the tool as read-only and non-destructive. The description adds meaningful behavioral context beyond that by specifying the draft is 'local' and that it 'never writes or sends mail', which clarifies the exact side-effect profile. 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 a single, tight sentence that front-loads the core purpose and immediately follows with the most important safety boundary. Every word earns its place; there is no redundancy or 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?

For a simple, read-only local preview tool, the description covers purpose and safety well. However, it does not mention what the tool returns or what an agent should expect after calling it, and there is no output schema to fill that gap. Parameter semantics are also left entirely to inference.

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 0% and the description does not explain any of the parameters: to, subject, body, or cc. The parameter names and types are visible in the schema, but the description adds no meaning beyond them. With low schema coverage, the description needed to compensate and did not.

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 uses a specific verb and resource: 'Prepare a local draft preview'. It also explicitly states a critical boundary: 'this tool never writes or sends mail', which clearly distinguishes it from any mail-sending or server-side draft 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 implies when to use it: when a local, side-effect-free draft preview is needed. However, it does not explicitly state when not to use it or name alternatives, such as mail_list_inbox for reading mail or a hypothetical send tool. The usage context is clear but not fully explicit.

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