create-mail-folder

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

Annotations already declare readOnlyHint=false and destructiveHint=true, indicating a write operation. The description adds valuable context beyond this: it specifies that folders are created at the root (top-level) and that isHidden can only be set at creation time. It does not mention side effects or error scenarios, but given the annotation coverage, a 4 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 two sentences plus a concise tip line. The main purpose is front-loaded, the hidden-folder condition is immediately relevant, and the tip efficiently lists alternatives and prerequisites. No redundant words or unnecessary details.

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, the combination of description and schema provides enough information: the description states the operation and location, and the schema details all body properties (including displayName and isHidden). However, the description does not explicitly state that displayName is typically required (it's not marked required in the schema), nor does it mention potential error cases. Given that the agent can infer from the schema, but the omission of a required-field note is a gap, a 3 is appropriate.

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 75% (body lacks a direct description, while confirm, includeHeaders, and excludeResponse have descriptions). The description adds the isHidden nuance (that it must be set on creation), but it does not clarify which body properties are essential (e.g., displayName). The schema itself describes the subproperties, so the description provides some value but does not fully compensate for the missing body description.

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 action ('create a new mail folder'), the resource ('mail folder'), and the location scope ('in the root folder of the user's mailbox'). It clearly distinguishes from the sibling 'create-mail-child-folder' by noting it creates only top-level folders, making the purpose unambiguous.

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 explicitly tells when to use this tool (for top-level folders) and provides alternatives: 'Use create-mail-child-folder to create a subfolder inside an existing folder' and 'Use list-mail-folders to find existing folder IDs.' It also gives a conditional instruction ('If you intend a new folder to be hidden, you must set the isHidden property to true on creation'). This is clear when/when-not guidance.

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