Label / mark / archive emails

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

Annotations already cover the safety profile (readOnly=false, destructive=false, openWorld=true), and the description reinforces this with 'Never deletes anything' plus a concrete definition of archive ('remove from Inbox; mail stays in All Mail'). It also discloses the 1000-id batch ceiling and the IMAP labels-as-folders caveat, which annotations do not. Missing is failure behavior on partial/invalid ids and whether conflicting flags (star+unstar) error.

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?

A single front-loaded sentence with the verb and resource first, and every clause carries information (operations, label syntax, batch limit, non-destructive guarantee). It is dense — one long multi-clause sentence — but nothing is redundant.

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 10-parameter bulk mutation with no output schema, the definition covers what it changes and what it won't destroy, but omits anything about return values (e.g., count of messages changed) and error/partial-failure semantics, which matter when up to 1000 ids are submitted at once.

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 only 40% schema description coverage across 10 parameters, the description does real work: it explains archive semantics, that labels may be given by name or id and are folders on IMAP, and the maxItems of 1000 for messageIds. It does not address the mutual exclusivity of star/unstar or markRead/markUnread, nor the account fallback, so it improves on the schema rather than fully compensating.

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?

Names a specific verb and resource ('Change messages in one account') and then enumerates every mutation it performs: mark read/unread, star/unstar, archive, move to Inbox, add/remove labels. That enumeration clearly separates it from read-side siblings (search_emails, read_email) and from delete_draft or bulk_cleanup.

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?

Usage is implied by the operation list and the 'up to 1000 message ids' batching note, but there is no explicit when-to-use guidance or named alternative (e.g., 'get ids from search_emails first, use bulk_cleanup for rule-based cleanup'). The IMAP aside does clarify one context where behavior differs, which lifts it above a bare 2.

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