List mailboxes

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the bar is lower. The description adds useful context about localisation and case-sensitivity, and indicates that unread counts are included, which are behaviors not captured by annotations.

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?

Three concise sentences front-load the core purpose, then provide a usage tip and a return format. Every sentence earns its place, and the localisation examples are valuable without being verbose.

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 read-only list tool with one optional parameter, the description covers what it does, when to use it, and the return structure. The output schema and annotations cover the rest, making this complete.

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 input schema covers the lone 'account' parameter fully with a clear description, so the baseline is 3. The description only adds 'optionally for one account,' which partially restates the optional nature but adds little 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 states a specific verb and resource: 'List mailboxes (folders) with their unread counts, optionally for one account.' This clearly distinguishes it from sibling tools like apple_mail_list_accounts and apple_mail_search_messages.

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?

It explicitly advises 'Use before searching a non-inbox folder' and explains why (case-sensitive, localized names). However, it does not mention when not to use the tool or explicitly compare it to alternatives like apple_mail_unread_summary.

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