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

Annotations declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the mutation profile is largely covered. The description adds only the 'without moving it' behavior, with no mention of permissions, collision handling, or whether renaming affects children/rules.

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 that is efficient, though it errs on the side of under-specification rather than richness.

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 3-parameter mutation tool with no output schema and two undocumented parameters, the description omits how to identify the folder, what a successful result looks like, and failure modes. It is too thin for the schema gaps.

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 only 33%: mailbox is well documented and points to list_authorized_mailboxes, but folderId and displayName have no descriptions. The tool description does nothing to fill that gap, e.g. how to obtain folderId or any naming constraints.

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 (rename) and resource (mail folder) and adds a scope note ('without moving it') that clarifies it's a pure rename. It doesn't explicitly distinguish itself from siblings like move_messages or merge_mail_folders, so it stops short of 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?

No guidance on when to use this versus alternatives (rename_gmail_label, merge_mail_folders, move_messages) or prerequisites such as needing an existing folder id. The scope clause implies a constraint but is not usage routing.

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