MCP Email Service

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

With no annotations provided, the description carries the full burden. It discloses network latency and mailbox requirements, which are useful behavioral traits, but does not cover aspects like error handling, attachment size limits, or output format. It adequately hints at a read operation but lacks depth for a tool with potential complexities.

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 front-loaded with the core purpose in the first clause and efficiently adds two contextual sentences. Every sentence earns its place by providing essential information without redundancy, making it appropriately sized and well-structured.

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 no annotations and no output schema, the description is moderately complete. It covers purpose and some behavioral context but lacks details on return values, error cases, or deeper operational constraints. For a tool with 3 parameters and potential network interactions, more information would enhance completeness.

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 description coverage is 100%, so the schema fully documents the three parameters. The description does not add any parameter-specific details beyond what the schema provides, such as explaining email_id format or folder options. Baseline 3 is appropriate as the schema handles the 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 specific action ('Extract attachments') and resource ('from an email'), distinguishing it from sibling tools like get_email_detail or get_email_headers. It specifies the method ('by downloading them over IMAP'), making the purpose unambiguous and distinct.

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 it ('Requires a reachable mailbox') and mentions a performance consideration ('may incur network latency'), but does not explicitly state when not to use it or name alternatives among siblings like get_email_detail for non-attachment data.

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