mail_folders

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety and external-system profile is covered. The description's only added behavioral signal is that results include special-use flags, which hints at the return shape but gives no detail on format or completeness.

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 short sentence that front-loads the verb and resource with no filler. Nothing could be removed without losing information.

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 parameterless, read-only listing tool with no output schema, the description conveys what is returned ('folders' and 'special-use flags') sufficiently for an agent to know what it will get. Minor omission: no note on whether folders are hierarchical or how they should be referenced in subsequent calls.

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 exposes only an empty 'arguments' object, i.e. effectively zero meaningful parameters, so there is nothing for the description to clarify. Baseline 4 applies for a parameterless call.

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?

States a specific verb+resource ('List iCloud mail folders') and additionally names the payload ('special-use flags'), which is more precise than a bare 'list folders'. It is clearly distinct from siblings like mail_search or mail_senders, though it does not explicitly call out that distinction.

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?

There is no when-to-use or when-not-to-use guidance. An agent can infer that this is a discovery call that might precede mail_move or mail_search, but the description never states that or tells the agent what to do with the result.

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