list_mailboxes

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds that the tool returns exact names rather than approximate ones, which is a useful behavioral nuance. However, it doesn't disclose other traits like auth requirements or rate limits, so a 3 is appropriate given the annotation coverage.

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 short sentences, front-loaded with the main action ('List exact mailbox names') and followed by a practical usage note. Every word earns its place, with no filler or redundancy.

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?

The tool is simple and has annotations plus an output schema to reduce the burden, but the description misses the connection between account_id and the sibling list_accounts tool. This gap could lead an agent to call the tool with an incorrectly sourced account_id, so completeness is moderate.

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 schema description coverage is 0%, so the description must compensate, but it doesn't mention the required account_id parameter at all. While the parameter name and title are somewhat self-explanatory, the description fails to clarify how to obtain the account_id (e.g., from the sibling list_accounts tool), leaving ambiguity for an agent.

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 that the tool lists exact mailbox names, with an explicit verb ('List') and resource ('mailbox names'). It distinguishes from siblings like list_accounts by focusing on mailboxes rather than accounts, and the word 'exact' conveys precision. However, it doesn't explicitly name sibling alternatives for contrast, so it misses a 5.

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 phrase 'use these names rather than guessing them' provides direct usage guidance, telling the agent to call this tool to obtain canonical mailbox names before referencing them elsewhere. This is clear context for when to use the tool, though it doesn't explicitly discuss when not to use it or mention alternative tools.

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