forward_email

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

Beyond the annotations (which only say it is a non-readOnly, non-destructive, non-idempotent open-world call), the description discloses the concrete outcome: automatic 'Fwd:' subject prefix, original headers and plain-text body inlined below the note, and original attachments re-attached unless include_attachments is false. It also states the message is sent immediately and requires user confirmation — exactly the context an agent needs for an irreversible external send.

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?

Purpose and the confirmation requirement are front-loaded, then content-transform behavior, then a parameter list that earns its space because the schema has no descriptions. Slightly verbose in the Args block, but nothing is wasted given the coverage gap.

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 9-parameter mutation tool with no output schema, the description covers what gets transformed, what gets sent, required confirmation, and parameter defaults. Gaps are minor: no statement of what the tool returns (sent message / UID), how folders should be resolved, or what happens on invalid recipients.

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?

With 0% schema description coverage across 9 parameters, the description carries the full burden and mostly meets it: it explains the distinction between 'attachments' (extra local files) and 'include_attachments' (re-attach originals, default true), the default for body, and cross-references list_accounts for the account value. The weaker spots are 'folder' (no hint that list_folders/resolve_folder produce it) and 'uid' (no format note).

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 opens with a specific verb and resource — 'Forward a message to new recipients and send it immediately' — and the word 'forward' plus 'to new recipients' cleanly distinguishes it from reply_email and send_email in the sibling list. An agent can select it without opening the schema.

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 with the user first' gives real pre-invocation guidance, which is valuable for an outward-facing send. However, there is no explicit statement of when to prefer forward_email over reply_email or send_email, and no prerequisites (e.g. needing to resolve the folder first via list_folders/resolve_folder).

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