Send Email

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

Annotations indicate the tool is mutating and not idempotent. The description adds context about SMTP transport, supported email fields, and that it returns a messageId on success. It does not cover rate limits or delivery behavior, but the added details are sufficient for basic transparency.

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 sentence that front-loads the core purpose and concisely lists supported features. Every part adds value, with no redundancy or unnecessary detail.

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?

Given 10 parameters and an existing output schema, the description covers the main purpose and supported options. It lacks details on error handling, sender identity, or immediate sending behavior, but is still fairly complete for a standard email send 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 coverage is 100%, so parameters are already documented. The description reinforces that addresses are comma-separated and attachments are base64-encoded, adding slight extra meaning. However, it does not substantially improve understanding beyond the schema.

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 action ('Send an email via Proton Mail SMTP') and specifies the resource (email). It lists supported features like To/CC/BCC, HTML, priority, and attachments, distinguishing it from sibling tools like forward_email or reply_to_email which have different purposes.

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 does not provide guidance on when to use this tool versus alternatives such as forward_email, reply_to_email, schedule_email, or save_draft. It only describes functionality, leaving the agent to infer usage without explicit decision criteria.

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