list_foldersList mail folders on the account with their names and message counts to verify a folder exists before referencing it. Avoid guessing by checking available folders.
List the mail folders on this account with their names and message counts. Use it when a task names a folder you have not seen, rather than guessing that it exists.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark it read-only and non-destructive. The description adds useful behavioral context by stating the scope ('on this account') and the return contents (names and message counts). No contradictions with annotations.
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, no wasted words: the first states exactly what the tool returns and the second gives a practical usage rule. It is front-loaded and easy to parse.
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 zero-parameter read-only listing tool, this description is complete: it names the output fields, the account scope, and the condition under which an agent should invoke it. No output schema exists, but the described return content is sufficient.
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 tool takes zero parameters, so the empty schema fully covers parameter semantics. The description adds the only relevant contextual scope, 'on this account,' which warrants the baseline-4 score.
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 opens with a specific verb and object: 'List the mail folders on this account with their names and message counts.' This clearly identifies the resource and output, and distinguishes it from sibling tools like list_messages or list_events.
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?
It gives a clear trigger: use it when a task names a folder you have not seen, rather than assuming it exists. It does not name specific sibling alternatives or explicit when-not-to-use cases, but the context is unambiguous.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.