Create Gmail draft

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

Annotations only declare the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false, openWorldHint=true). The description goes further by stating the side effect boundary ('creates a draft only. Does not send'), the success payload shape (draft_id, message_id, thread_id, provider), and the concrete failure taxonomy (VALIDATION_ERROR, AUTHENTICATION_REQUIRED, AUTHORIZATION_DENIED, GOOGLE_API_ERROR). That is real added value beyond the structured fields.

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 one-line purpose is front-loaded, followed by clearly labeled blocks for usage, parameters, side effects, returns, and failures. Efficient and scannable, though the parameter restatement and failure list add some redundancy with the schema.

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?

With no output schema, the description compensates by naming the returned identifiers and provider, and it covers the mutation's side-effect boundary and error surface. An agent has everything needed to call this correctly for a 7-parameter mutation tool.

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 both schema and description document all seven parameters, setting the baseline at 3. The description restates required vs optional and the is_html default, which largely duplicates the schema rather than adding syntax or format meaning beyond it.

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 ('Create a draft email') and immediately scopes it as 'without sending it.' The 'Prefer this over gmail_send_email' line explicitly differentiates it from a named sibling, so an agent can disambiguate without opening either schema.

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 an explicit when-to-use block plus a named alternative (gmail_send_email) and the exact condition that selects it (user has not confirmed sending). This is the full when/when-not/alternative triad.

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