send_email

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

Annotations already declare it is a non-read-only, non-destructive call, and the description adds real behavioral context: the call blocks on the SMTP server's answer, and a recipient the server rejects is surfaced later as a delivery failure in receive_email. It does not discuss timeout defaults or rate/connection failure modes, but the added detail goes clearly beyond the annotations.

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?

Two sentences, no filler, and the action plus prerequisite are front-loaded before the failure-handling note. Every clause earns its place.

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?

An output schema exists, so return values need not be explained, and the mutation's safety profile is covered by annotations. The description supplies the prerequisite and the delayed-failure semantics, which is enough for an agent to call it correctly; only timeout/error behavior is left implicit.

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 60%; 'to', 'device' and 'timeout_secs' are documented in the schema while 'subject' and 'body' are not. The description reinforces the device/account linkage but adds no syntax, format, or constraint detail beyond what the schema already provides, so the baseline 3 is appropriate.

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') and pins the sending account to the one created by configure_email. It also names the sibling receive_email as the eventual failure channel, so the agent can place it in the workflow without reading further.

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?

Implies the prerequisite (account must be set up with configure_email) and explains the asynchronous failure path via receive_email. It doesn't spell out when-not to use it, but it is the only send tool among the siblings, so the routing burden is low.

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