list_mailboxes

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

The description states the return fields (id, name, total message count, unseen count) which adds value beyond the output schema. However, with no annotations, it fails to disclose potential side effects, permissions needed, or reliability considerations (e.g., pagination, real-time vs cached data).

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 exceptionally concise: two sentences with no extraneous words. The first sentence delivers the core purpose, and the second covers prerequisite and return info. Every part earns its place.

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 simplicity (single parameter, output schema present), the description covers the essential aspects: action, required input derivation, and return content. It lacks details like error handling or performance notes, but for a straightforward list tool, it is sufficiently 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 has 0% description coverage for the account_id parameter. The description compensates by explaining that account_id comes from list_accounts, providing essential context for the agent to select the correct parameter value. This significantly adds meaning beyond the raw 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 tool lists mailbox folders (INBOX, Sent, etc.) and what it returns. It is specific about the action and resource, but does not explicitly differentiate from sibling tools like get_email or search_emails, which limits clarity in distinguishing use cases.

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 a prerequisite hint ('Use list_accounts to find account_id') which guides the user on required prior action. However, it does not specify when to use this tool versus alternatives (e.g., get_mailbox_stats) or when not to use it, leaving some ambiguity.

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