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

Annotations already disclose that this is a non-read-only, non-idempotent, non-destructive write operation. The description confirms creation and optional nesting but adds no further behavioral context such as duplicate-name handling, parent-existence requirements, permissions, or response behavior.

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 a single front-loaded sentence with no wasted words. It states the action and optional nesting immediately.

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 tool with full parameter documentation and clear annotations, the description is minimally adequate. However, with no output schema, it does not explain what creation returns, and it omits error or duplicate-handling context that could matter for a non-idempotent write.

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 100%, so both parameters are already documented by the schema. The phrase 'optionally nested under another' reinforces the parentId relationship but does not add meaning beyond the schema's 'Parent folder ID for nesting.'

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 gives a specific verb and resource: 'Creates a folder', and adds the key scope detail that it can be nested. It is clear enough to distinguish from sibling operations like mailbox_delete and mailbox_rename, but it does not explicitly say 'mailbox folder' or otherwise differentiate itself from other create-style tools.

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 only usage guidance is that nesting is optional, which really describes a parameter rather than when to choose this tool. It does not name alternatives, prerequisites, or conditions such as when to use mailbox_create versus other create operations.

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