send_email

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

No annotations are present, so the description carries the full burden, and it delivers: it discloses accepted-vs-delivered asynchronous semantics, webhook or read-back completion, header visibility for cc, the guaranteed absence of bcc from headers, and the attachment limitation. This is unusually rich behavioral disclosure.

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 compact and well-ordered: primary action up front, then essential delivery semantics, then recipient visibility behavior, then the attachment limitation. Every sentence earns its place without redundancy.

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 7-parameter tool with no output schema and no annotations, the description provides enough about sending semantics, result timing, delivery confirmation, and parameter nuances. The missing detail on body and subject formatting is minor relative to the coverage provided.

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 schema has no parameter descriptions, and the description adds meaning to `address`, `html`, `cc`, and `bcc`, but `to`, `body`, and `subject` remain only name-implied. It compensates partially but does not fully document all seven parameters.

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 clear action and resource: sending an email from a specified inbox address, with DKIM signing mentioned. It positions the tool for replies and outbound automation but does not explicitly distinguish it from the sibling 'reply' tool, so it misses full sibling differentiation.

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 gives explicit when context with 'Use for replies or outbound automation' and points users to the SDK for attachments, which is a useful limitation. However, it does not explain when to prefer the sibling `reply` tool, so the guidance stops short of a full alternatives map.

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