undo_move

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

Annotations already flag this as destructive, non-idempotent, and not read-only, so the safety profile is covered. The description adds one genuinely useful behavioral detail absent from annotations: Gmail messages return to All Mail, not the inbox. However, it never explains why the tool is destructive (e.g., that it can overwrite a message's current location or labels), leaving the annotation's destructiveHint unelaborated.

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, zero waste, with the core reversal action and its sibling reference front-loaded before the Gmail-specific caveat. Each sentence 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?

With an output schema present, return values need no explanation, and annotations carry the safety profile. The description covers invocation modes and a non-obvious provider quirk, though it could say more about failure/expiry behavior for the undo token.

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 100% and the single token parameter is fully documented in the schema, including the 'omit to undo most recent' default. The description's 'by undo_token, or the latest move' largely restates that, adding no syntax or format detail beyond the schema.

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 uses a specific verb ('move messages back') tied to a named sibling ('before a move_mail call'), so an agent can immediately distinguish this reversal tool from move_mail itself. The parenthetical clarifies both invocation modes (token or latest).

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 clearly frames usage as undoing a prior move_mail and explains the two selection modes (explicit undo_token vs. latest move). What's missing is any exclusion guidance, such as what happens if no prior move exists or when a token has expired.

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