List folders

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered without prose help. The description adds only mild context by naming example folder types, and says nothing about whether the result is a flat list or a folder tree, ordering, or 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?

One front-loaded sentence with no filler; the resource and scope appear immediately and the parenthetical examples do real work. It is borderline terse rather than padded, which is a completeness issue rather than a conciseness one.

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 single-parameter read tool with annotations and no output schema, the essentials are present, but an agent still cannot tell from the description whether the result includes nested/child folders, folder IDs for reuse elsewhere, or unread counts — details that affect how it composes with read_email and search_emails.

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?

There is a single parameter and schema description coverage is 100%, so the schema already explains 'account' with an example address format. The description adds nothing about the parameter; per the rubric, full schema coverage sets the baseline at 3.

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?

Clear verb+resource ('List folders') scoped to a mailbox, with parenthetical examples (Inbox, Sent, Drafts) that pin down what a 'folder' means here. It implicitly distinguishes itself from list_attachment_folders by saying 'of a mailbox', but never names that sibling, so the differentiation is left to inference.

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?

Usage is only implied: the examples of Inbox/Sent/Drafts suggest this is the discovery step before read_email or search_emails, but the description states no when-to-use condition, no prerequisite that an account address is required, and no pointer to list_attachment_folders as the alternative for attachment directories.

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