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

With no annotations provided, the description carries the full burden. It does disclose a meaningful behavioral scoping rule (parent-scoped only, cross-parent duplicates ignored), but it does not state whether the operation is read-only, what the result format is, or whether it returns folder IDs needed for merging.

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 description is two sentences with no filler. The core behavior is front-loaded, followed immediately by the clarifying negative case.

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 one-parameter read-style finder, the description covers what it returns conceptually, what it excludes, and why. The only gap is the absence of output shape details, especially since there is no output schema, which prevents a 5.

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 mailbox parameter already has a detailed schema description, including a pointer to list_authorized_mailboxes. The tool description adds no parameter-level detail, so baseline 3 is appropriate.

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 names a specific action and resource: 'Find folders that share a name within the same parent.' It also distinguishes itself from find_duplicate_gmail_labels (different resource) and makes the intent explicit with 'likely duplicates worth merging.'

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 gives clear context for when to use the tool and explicitly states the exclusion: folders with the same name under different parents are not reported. However, it doesn't name alternative tools such as list_mail_folders or the follow-up merge_mail_folders, so it stops short of full routing guidance.

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