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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds purpose and IMAP importance, but does not disclose pagination behavior (limit/cursor) or the exact return format, which would be useful for a read operation. Since annotations cover the main safety aspects, a 3 is appropriate.

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 concise and front-loaded with the core purpose, followed by a warning and an ID clarification. The 'Mailbox folder/label ID' sentence is somewhat redundant but not excessive. It earns its keep without being verbose.

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 read-only lookup tool, the description does not specify the output structure (e.g., list of {name, id} pairs) or explain the limit/cursor parameters. Given no output schema and low parameter coverage, an agent lacks critical information to correctly parse results or handle pagination. The tool is simple, but the description leaves notable 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 description coverage is only 33% (only account_id has a description). The description does not explain limit or cursor semantics at all, and it adds no parameter-specific guidance beyond what the schema already provides for account_id. With low coverage, the description was expected to compensate but fails to do so.

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 clearly states the verb (list/map) and resource (mailbox folders/labels) with the specific goal of mapping human names to exact folder_id. It differentiates from siblings like email_list_folders by framing this as a resolution step before operations that need IDs, and explicitly warns against passing human names when an ID is required.

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?

Provides explicit when-to-use context ('before moving/labeling or listing folder messages') and a clear warning ('Never pass: human folder name...'). It references email_list_folders as the source of folder.id, implying the distinction. However, it does not explicitly state when to use email_list_folders instead of this tool, leaving a slight gap.

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