Inbound Email MCP Server

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

Annotations already indicate read-only, idempotent, and non-destructive behavior, which the description does not contradict. The description adds valuable context beyond annotations by specifying the requirement for the 'x-inbound-mailbox header,' the default sorting ('unread emails shown first by default'), and the inbound filtering ('emails sent TO your mailbox address'), enhancing transparency without redundancy.

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 sentence, followed by prerequisites and behavioral details in subsequent sentences, all without wasted words. Each sentence adds essential information (e.g., header requirement, filtering scope, default sorting), making it highly efficient 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 the tool's moderate complexity (4 parameters, no output schema) and rich annotations (read-only, idempotent), the description is largely complete, covering purpose, prerequisites, and key behaviors like default sorting. However, it lacks details on response format or error handling, which could be useful since there's no output schema, leaving a minor gap.

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%, with all parameters well-documented in the schema (e.g., status filter with default 'unread', limit range, offset for pagination, time range options). The description does not add any parameter-specific details beyond what the schema provides, so it meets the baseline for high schema coverage without extra value.

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 ('check'), resource ('agent mailbox'), and scope ('for incoming emails'), distinguishing it from siblings like 'list_emails' or 'get_email' by focusing on the agent's own mailbox with inbound filtering. It explicitly mentions 'emails sent TO your mailbox address,' which clarifies its unique role.

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 usage by specifying 'Requires the x-inbound-mailbox header to be set' and that it returns 'emails sent TO your mailbox address,' which implicitly differentiates it from tools like 'list_emails' that might list all emails. However, it does not explicitly state when not to use it or name alternatives, such as 'get_email' for specific emails.

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