Create a mail draft

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

Annotations already indicate this is a mutating, non-idempotent, non-destructive operation. The description adds valuable context beyond annotations: nothing is transmitted, the draft is unsent, and the tool returns id and webLink. This meaningfully clarifies the tool's side effects.

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 sentences with no filler. The core behavior is front-loaded, and each sentence adds distinct value: what it creates, what it cannot do, and how recipients behave.

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 create-draft tool with a fully documented schema, the description covers the essential behavioral context: return values, non-sending behavior, and the fallback path. It does not explain error conditions or permissions, but those are not necessary for correct invocation here.

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 100%, so the schema already documents all six parameters. The description adds the useful note that recipients are optional, but does not need to explain each parameter further. Baseline 3 is appropriate.

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?

States a specific verb and resource: creates an unsent draft in the Drafts folder. It explicitly differentiates itself from mail_send by noting it cannot send, so an agent can distinguish it from the sibling tools without opening schemas.

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?

Provides explicit guidance on when to use this tool versus mail_send, and notes that there is no companion tool to send an existing draft. It also clarifies that recipients are optional, which is directly useful for invocation decisions.

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