smtp_forward_message

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

With zero annotations, the description carries the full burden, and it does disclose the most consequential trait for a send tool: a mandatory user-preview and explicit-confirmation gate, which signals that this produces an irreversible outward-facing effect. It omits other behavioral facts an agent would want — which account/auth is exercised, what happens on delivery failure, whether original attachments are preserved — keeping it below a 5.

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: the action is stated first, then the safety precondition. Every clause earns its place and the confirmation requirement is placed where an agent will read it before acting.

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 no explanation, and the schema fully covers the five parameters. Combined with the confirmation workflow, the definition is sufficient to call the tool correctly; only secondary details (account selection semantics, attachment carry-over) are 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 description coverage is 100%, so the schema already documents every parameter in detail, including the body_text vs body_html quoting distinction. The description adds nothing parameter-specific; its '(To, CC, BCC, subject, rendered body, attachments)' list describes preview contents rather than actual inputs (only `to` is a parameter), so it does not exceed the baseline.

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 states a specific verb and resource — 'Forward an existing message' — plus the transport ('via SMTP'), which is enough to separate it from smtp_send_message and smtp_reply_message by name. It stops short of explicitly naming those siblings or drawing the contrast, so it lands at clear-but-undifferentiated rather than a 5.

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?

It gives a concrete procedural precondition: preview the full message and obtain explicit user confirmation before calling. That is real when/how guidance, but there is no explicit exclusion or routing rule in the description itself (the 'use smtp_send_message if you need the original embedded in HTML' alternative lives only in the schema, not here).

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