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

No annotations are provided, so the description carries the full burden. 'List' clearly implies a safe read operation, and it hints at the return shape (paths), but it does not state read-only status, whether results are paginated or ordered, or any auth/permission requirements.

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?

One sentence, front-loaded with the resource, with the downstream usage packed into the same clause. No filler.

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 single-optional-param listing tool with no output schema, the description adequately covers what it returns (folder paths) and why. It stops short of describing ordering or whether nested label hierarchies are flattened, which would matter for some agents.

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 optional 'mailbox' parameter is fully documented in the schema, including the fallback behavior when only one account is connected. The description adds nothing about parameter semantics beyond what the schema already states, so the 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?

Names a specific verb and resource (list folders of a mailbox) and grounds it with concrete examples (INBOX, Sent, Archive, labels). It also states what the output is for, making it easy to distinguish from siblings like mail_accounts.

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?

Implies the workflow position clearly: the returned paths are 'to pass to mail_search and mail_read', which tells the agent when this tool precedes others. It does not explicitly contrast with mail_accounts, whose mailbox-listing role is only mentioned inside the parameter description.

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