Email Save Draft

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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=true. The description adds the key behavioral fact that the message is not sent and is saved to Drafts, which is useful. However, it doesn't disclose details like whether an existing draft is overwritten, how the draft is identified in responses, or any side effects beyond saving. With annotations covering the safety profile, a 3 is appropriate.

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 sentence with no wasted words. It front-loads the core action ('Save a message to the Drafts folder without sending it') and adds the user benefit ('so the user can review and send it from any mail client') in a compact clause. Every word earns its place.

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?

The tool has 9 parameters, 100% schema coverage, an output schema, and annotations. The description is brief but sufficient for a draft-saving tool: it clarifies the non-sending behavior and the purpose. It doesn't explain return values, but the output schema exists, so that's not required. It could mention that 'to' may be omitted (schema already says this) or clarify attachment behavior, but the schema covers those. Overall, complete enough for an agent to call it correctly.

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 9 parameters. The description adds no parameter-specific meaning beyond what the schema provides. Baseline 3 is correct when the schema does the heavy lifting. The description's mention of 'review and send from any mail client' adds context but not parameter semantics.

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 the tool's purpose: 'Save a message to the Drafts folder without sending it.' It uses a specific verb ('save') and resource ('message to the Drafts folder'), and distinguishes it from sending by explicitly noting 'without sending it.' This differentiates it from the sibling tool email_send.

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 this tool: when the user wants to save a draft for later review/sending from any mail client. It doesn't explicitly name alternatives or exclusions, but the contrast with 'without sending it' and the sibling email_send provides clear context. It could be improved by explicitly saying 'use email_send to send immediately,' but the current guidance is sufficient.

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