Send an email

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

No annotations are provided, but the description discloses that sending is immediate and non-confirmatory: 'this sends right away — there is no confirmation step.' It also implies irreversibility by advising careful consideration. It does not mention failure handling or permissions, but it covers the core behavioral trait.

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 two sentences, front-loaded with the purpose, and each sentence adds value: the first states the action, the second explains the immediate nature and gives an alternative.

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 simple send action with full schema and no output schema, the description covers the purpose, usage context, and behavioral nuance. It provides sufficient context for an agent to decide when to use this tool versus create_draft.

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 input schema already describes all parameters with 100% coverage, so the description adds no additional parameter meaning. The description doesn't mention any parameter specifics, but the schema suffices.

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 function: 'Send a new email immediately from the signed-in mailbox.' It distinguishes from sibling create_draft by referencing alternative usage, making the purpose unambiguous.

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 explicitly provides when-not to use: 'Use create_draft instead if the message should be reviewed before sending.' It also advises certainty before calling: 'only call this once you (and the user, if appropriate) are sure about the recipients and content.'

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