update_draft

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

Annotations already mark destructiveHint=true, and the description aligns by saying 'Replace a draft'. It adds valuable behavioral detail: HTML restrictions (permits normal layout CSS but rejects remote resources, hidden content, message-box escapes) and that empty paragraphs are preserved. It also clarifies it cannot send emails – useful context beyond 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?

Three sentences, with the primary purpose front-loaded. It adds only relevant details about HTML constraints and capabilities, with no verbosity. Every sentence earns its place, making it highly efficient.

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 complex tool with 9 parameters and 0% schema coverage, the description is thin. It covers purpose and HTML constraints but omits parameter semantics, required field explanations, and side effects beyond replacement. The presence of an output schema doesn't offset the missing parameter guidance, so completeness is low.

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%, so the description must compensate, but it provides no information about any of the 9 parameters. It mentions 'authored HTML' but does not tie it to the html_body parameter. Required parameters like account_id, draft_id, to, subject, body are unexplained, leaving the agent without guidance on how to construct a valid call.

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 'Replace a draft' – a specific verb and resource. It clarifies scope with HTML constraints and 'No send capability', which helps distinguish from send-related tools. However, it does not explicitly name siblings like create_draft, though 'replace' implies updating an existing draft.

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?

No explicit when-to-use guidance is provided. The description implies use for updating existing drafts rather than creating new ones, but does not state conditions or alternatives. It also omits prerequisites like having a draft_id, so an agent must infer usage context.

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