list_folders

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

No annotations are provided, so the description carries the full burden; it discloses the concrete output format and, importantly, the non-obvious fallback behavior that a blank account auto-selects when exactly one account exists. It stops short of stating whether the call is read-only or what happens when multiple accounts exist and account is omitted.

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 compact sentences: the first front-loads the resource and the per-line output template, the second covers the single edge case. No filler or repetition of schema fields.

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?

Output schema exists, so return values needn't be explained, and the description still adds the human-readable line format. Behavior for the only parameter is covered for the single-account case; the multi-account, blank-argument case is the one gap remaining for a tool this simple.

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 0% and the single account param has no title or description in the schema, but the description supplies the essential semantic: leave it blank and a sole account is chosen automatically. The remaining ambiguity — how to choose among multiple accounts — is not addressed, so it falls short of full compensation.

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 and resource (列出账户的 IMAP 文件夹) plus the exact output shape '名称 (N封/M未读)', which tells an agent precisely what comes back. It is distinguishable from list_accounts and search_emails by the folder-oriented scope, though it never names those siblings explicitly.

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 implied by the resource: use this to enumerate folders and their counts. There is no explicit when-to-use rule, no mention of what tool to call first (e.g. list_accounts) or when to prefer search_emails, so an agent must infer the workflow position.

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