list_folders

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

No annotations exist, so the description carries the disclosure burden. It usefully flags the performance tradeoff of with_counts=True on large mailboxes, but says nothing about permission requirements or what the returned folder objects contain. 'List' implies read-only but that is never stated outright.

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 sentences, both front-loaded with the core behavior first and the conditional cost caveat second. 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?

For a one-parameter read tool with no output schema and no annotations, the description covers the essential action and the only parameter's tradeoff. A brief note on return shape (folder names/IDs) would close the remaining gap, but nothing critical to correct invocation is missing.

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 parameter's title is just 'With Counts', so the description must compensate — and it does, explaining that it adds message and unread counts per folder and that it is slower on large mailboxes. That is meaningful semantic and cost information absent from the schema.

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 ('List the mailbox folders') that unambiguously identifies the operation. It is clearly distinct from the message-oriented siblings (search_messages, get_message, get_thread), though it does not explicitly name them.

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 — an agent can infer this is the entry point for discovering folders before searching or reading messages. There is no explicit statement of when to call it, when not to, or which sibling to use instead.

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