gmail_forward

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

With no annotations, the description carries the full burden and does substantial work: it discloses that send is verified against Outbox/Sent, that an unclear state fails with 'send_state_unknown' without re-sending, and that verified_in may appear on the result. It does not state that forwarding is irreversible once sent, nor what happens when confirm is false beyond 'must be true'.

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 core action and scope are front-loaded into the first sentence, and the send-verification paragraph is dense but each sentence carries operational consequence. The confirm requirement is tacked on as a final line rather than integrated, a minor structural inefficiency.

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 13-parameter mutation tool with no annotations and no output schema, the description covers the highest-risk behavior (duplicate-send avoidance, confirm gate, error signal) and names the verification field on results. The lower-risk parameters (drive_files, attachments, expect_subject, draft_only) are left entirely to the 100%-covered schema, which is acceptable but means the description alone would not fully prepare an agent.

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 every one of the 13 parameters is already documented. The description adds a little framing ('with its attachments', 'to new recipients') and restates the message_index default, but adds no syntax, format, or interaction detail beyond what the schema properties already say. Baseline 3 applies.

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 ('Forward the last message of a conversation... to new recipients') and identifies the message_index variant, which implicitly separates it from gmail_reply/gmail_reply_all since the target is new recipients rather than the sender. It never names an alternative sibling outright, so sibling differentiation is inferred rather than stated.

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 does establish a hard precondition (confirm=true) and gives retry guidance ('check gmail.list folder='sent' before any retry'), which is real usage direction. It never says when to choose forward over gmail_reply, gmail_reply_all, gmail_send, or gmail_draft, and the draft_only escape hatch is only visible in the schema.

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