send_email

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

With no annotations, the description carries the full burden. It does disclose two useful traits — that user confirmation is required before sending, and that reply_to_message_id preserves the thread — but says nothing about irreversibility, required send permissions, or rate/account limits, which matter for an outbound mutation.

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?

Front-loaded with purpose and the confirmation rule, then a compact Args block; each line carries information rather than filler. It is appropriately sized for a 7-parameter tool.

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?

Covers purpose, most parameters, and one behavioral rule for a mutation tool with no annotations and no output schema. It stops short of the sibling differentiation (create_draft) and permission/irreversibility context that would make the definition fully self-sufficient.

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 description coverage is 0%, so the description must compensate, and it documents 5 of 7 parameters with genuine semantic detail: account as email-or-alias, to as comma-separated, subject allowed empty when replying with the 'Re: <original>' behavior, and thread preservation for reply_to_message_id. Only cc and bcc are left undocumented, and those are largely self-explanatory.

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 specific verb and resource ('Send an email from the given account'), which is unambiguous on its own. It does not, however, differentiate itself from the sibling create_draft, which an agent must choose between for outbound mail.

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?

'Confirm content with the user first' is a real usage directive and gives a prerequisite for invocation. But there is no explicit when-to-use guidance against the closest alternative, create_draft, nor any note on when a reply path (reply_to_message_id) should be preferred over a fresh send.

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