MCP Email Service

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

Since no annotations are provided, the description carries the full burden of behavioral disclosure. It effectively describes key behavioral traits: the requirement for 'live IMAP connectivity' (implying network dependency and potential failure modes) and the fallback behavior ('returns empty list when the mailbox cannot be reached'). It does not cover other aspects like rate limits, authentication needs, or pagination, but provides sufficient context for safe usage.

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?

The description is two sentences long, front-loaded with the core purpose and followed by important behavioral context. Every sentence earns its place by providing essential information without redundancy or fluff, making it highly efficient 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?

Given the tool's moderate complexity (listing folders with counts), lack of annotations, and no output schema, the description is reasonably complete. It covers the purpose, connectivity requirements, and failure behavior. However, it does not describe the return format (e.g., structure of the list, what 'unread counts' include) or potential errors beyond connectivity issues, leaving some gaps for an agent to infer.

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 input schema has 100% description coverage, with clear documentation for both parameters ('account_id' and 'include_empty'). The description does not add any additional meaning beyond what the schema provides, such as explaining the format of 'account_id' or elaborating on the implications of 'include_empty'. However, with high schema coverage, a baseline score of 3 is appropriate as the schema adequately handles parameter semantics.

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 verb 'List' and resource 'folders with unread counts per configured account', making the purpose specific and actionable. It distinguishes from sibling tools like 'list_folders' (which presumably lists all folders without unread counts) and 'list_emails' (which lists emails 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 clear context for when to use this tool ('Requires live IMAP connectivity') and what happens in edge cases ('returns empty list when the mailbox cannot be reached'). However, it does not explicitly state when NOT to use it or name specific alternatives among the sibling tools, such as 'list_folders' for a basic folder listing without unread counts.

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