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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds useful behavioral context by explaining that the returned folder.id is an exact Gmail label/Outlook/IMAP folder ID and that this listing is a preamble to message listing in IMAP. No contradiction with annotations exists.

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 opening sentences are efficient, but the tail block ('Mailbox folder/label ID: ...') reads like copy-pasted parameter documentation and is confusingly disconnected from this tool's input schema. It repeats the folder-id concept already stated, so the structure is not as clean as it could be.

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 list tool with no output schema, the description covers the essential operational facts: what is listed, why the returned IDs matter, and how this fits into IMAP message listing. It does not describe pagination or the full return shape, but the cursor schema and annotations compensate reasonably.

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 at 67%, and the schema already documents cursor and account_id well; limit has no description. The description's 'Mailbox folder/label ID' block is more about output semantics than the current tool's parameters, so it adds only marginal value for parameter understanding. 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 states a specific verb and resource: 'List Gmail labels, Outlook folders or IMAP folders.' It goes beyond a simple label by explaining the output's role ('Returned folder.id is required by folder-specific operations'), which clearly differentiates this list tool from folder mutation or message-listing siblings.

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?

The description gives concrete usage context: 'For IMAP this is normally the first step before listing messages' and warns 'Never pass: human folder name such as Inbox when an ID is required.' However, it does not explicitly name alternatives like email_resolve_folder or email_get_folder, so the when-to-use guidance is strong but not fully explicit.

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