Draft a message

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

Beyond the annotations, the description discloses that the operation only leaves a draft, does not transmit anything, can be read and changed later, and returns a draft id. These are non-obvious behaviors that materially affect how an agent plans its work.

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?

Three tight sentences front-load the core purpose and non-sending behavior, then give the prerequisite and return-value handoff. No filler or repetition.

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 3-parameter tool with no output schema, the description covers the key context: what is created, what is not done, the prerequisite address resolution, and the returned draft id. It does not cover every possible edge case, but it is sufficient for correct selection and 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?

The schema already documents 'to' as 'recipient addresses from resolve_person' and body as 'plain text'. The description does not add much beyond that, and the subject parameter has no useful schema description and no additional explanation in the description. Parameter semantics are adequate but not expanded.

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 states a specific action ('Create a draft message') and immediately clarifies what it is not: it does NOT send anything, so it cannot be confused with send_draft or reply_draft. This clearly differentiates the tool from its siblings.

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?

It gives an explicit precondition ('Get every recipient address from resolve_person first') and explains the downstream handoff ('send_draft takes if the message is later approved'). This tells an agent exactly when and in what sequence to use the tool.

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