fastmail_list_folders

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

With no annotations, the description itself must communicate behavior. It correctly indicates a read-only listing operation, but it does not disclose output shape, whether hidden or system folders are included, ordering, or error behavior. Still, for a zero-parameter list tool, the core behavior is transparent enough.

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?

A single four-word sentence conveys the operation and scope with no filler. It is front-loaded and easy 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?

Given the tool's low complexity, no parameters, and sibling context, the description is nearly complete for selecting and calling the tool. A minor gap is the lack of explicit return-format detail since no output schema exists, but 'List all email folders' sufficiently implies a returned collection of folders.

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?

The tool has zero parameters and schema coverage is 100%, so there is no parameter information to add. The baseline of 4 applies because the description does not need to compensate for undocumented parameters.

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 uses a specific verb ('List') with a clear resource ('all email folders'), and the resource type distinguishes it from sibling tools such as fastmail_list_emails and fastmail_get_account. The scope ('all') also signals a no-filter enumeration.

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 intended use is implied: call this when the agent needs the complete set of email folders. However, the description does not explicitly state when to prefer it over alternatives, mention related workflow steps (e.g., using folder IDs with fastmail_list_emails), or provide exclusion criteria.

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