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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the description does not need to restate these. It adds a useful constraint about parent_id not being a display name, which clarifies parameter behavior. However, it does not disclose potential side effects like duplicate handling or whether the operation is reversible, which would be helpful given it is a mutation.

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: one sentence for purpose and one for the critical parent_id constraint. It is front-loaded with the primary action and contains no filler. Every sentence adds value, making it efficient for an agent to parse.

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 simple create operation with 3 parameters, the description is adequate. It explains the purpose and the key constraint on parent_id. However, it does not mention what happens when parent_id is omitted (e.g., creates at root level) or what the return value is (since no output schema exists). These are minor gaps given the tool's simplicity and the schema's coverage.

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 67% (parent_id and account_id are described). The description adds a redundant clarification about parent_id being an exact ID from email_list_folders, which is already in the schema. It adds no information about the 'name' parameter. Since the schema already covers most parameters, the description adds marginal value beyond the schema.

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 'create' and the resource 'mailbox folder/label', which distinguishes it from sibling tools like email_delete_folder, email_update_folder, and email_list_folders. It is specific enough to avoid confusion with other email actions, though it could be more explicit about creating a new folder vs. other folder operations.

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 provides no guidance on when to use this tool versus alternatives. It does not mention that this is the tool for creating folders while others are for updating or deleting, nor does it state any prerequisites beyond the parent_id note. The parent_id note hints at needing email_list_folders, but it does not clarify usage context relative to siblings.

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