gmail_send_message

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

Annotations already mark the call as a non-read-only, non-idempotent mutation. The description adds the important behavior that the send happens immediately with no API-side confirmation and instructs user confirmation, plus it discloses the return payload. This goes beyond the annotations without contradicting them.

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 short, focused sections lead with the action, follow with the safety/usage caveat, and finish with return value. No filler or duplication of schema content.

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 side-effectful send tool, it covers what the call does, the immediate/no-confirmation behavior, the needed user confirmation, and the return format. Combined with the schema descriptions, an agent has everything needed to select and invoke 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?

The description itself adds no parameter-level detail, but the nested input schema documents all five fields (to, cc, bcc, body, subject) with descriptions and requiredness. The top-level params wrapper is unnamed in the description, so the schema carries the burden; 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?

The first sentence names a specific action ('Send... an email') and the account scope ('authenticated Gmail account'), and the second sentence contrasts it with draft/confirmation flows. This clearly distinguishes it from siblings like gmail_create_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?

It states the key usage condition (send immediately, no draft/confirmation) and instructs the agent to confirm intent before calling. It does not explicitly name alternative tools or spell out when to prefer gmail_create_draft, so it stops short of a 5.

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