send_email

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

The description discloses detailed behavioral traits beyond annotations: per-recipient SMTP delivery status (succeeded/failed/unknown), independent handling of the Sent-copy outcome, and no automatic retry for ambiguous effects. This significantly enriches the safety and operational understanding beyond the simple write intent implied by readOnlyHint=false.

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 dense sentence that front-loads the primary action, briefly mentions reply threading, and then provides crucial delivery report details. Every clause adds value with no repetition or filler.

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 description covers the core action, reply threading, and complex delivery reporting, which are essential for a sending tool. It does not mention environment dependencies (e.g., allowed recipients, attachment path resolution) that might be relevant, but the output schema exists and the description is strong overall.

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 has 100% parameter description coverage, so the schema already explains all 11 parameters. The description does not add any parameter-specific details beyond the schema, meriting the baseline score of 3.

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 a specific action ('Send one email using the specified account') and adds the capability of reply threading. This distinguishes it from sibling tools that list, retrieve, save, or delete emails.

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 usage by stating the action ('Send one email'), but it does not explicitly mention when to use this tool versus alternatives (e.g., save_to_mailbox, list_available_accounts). No exclusions or prerequisites like allowed recipients are mentioned, though sibling tools (list_allowed_recipients) suggest such constraints exist.

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