list_mail_folders

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the safety profile is covered. The description adds useful behavioral context: it only lists the user's own folders, supports a parent folder filter, and instructs to follow nextCursor for pagination.

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?

Two short sentences with no filler. The primary purpose is front-loaded, and the pagination note is appended cleanly. Every word 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?

For a simple read-only list operation, the description covers the core functionality and pagination. It doesn't specify return format, but no output schema exists and the annotations already convey the safe nature. Slight gaps on error handling and authentication are acceptable given the simplicity.

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?

Schema coverage is 100%, with both cursor and parentId adequately described in the input schema. The description adds no additional parameter details beyond echoing 'exact folder ID' for parentId, so it meets the baseline without exceeding it.

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 action (list) and resource (mail folders), and specifies two modes: listing the user's own folders or children of a specific folder ID. This distinguishes it from siblings like list_mail_messages, which operate on messages rather than folders.

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 context for when to use the tool (listing folders, optionally children of a given ID) and mentions pagination via nextCursor. It doesn't explicitly name alternatives, but the resource type is clear enough to differentiate from message-listing tools.

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