Inbound Email MCP Server

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

Annotations indicate this is a non-read-only, non-idempotent, non-destructive tool, which the description aligns with by describing a sending action. The description adds valuable context beyond annotations, such as support for HTML/plain text, CC/BCC, and scheduled sending with natural language times, though it doesn't cover rate limits or authentication details explicitly.

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 a single, well-structured sentence that efficiently covers the tool's key features without redundancy. It is front-loaded with the core purpose and includes only essential details, making it highly concise 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 complexity (10 parameters, no output schema) and rich annotations, the description is reasonably complete. It covers the main functionality and constraints (e.g., verified domain), but could be more comprehensive by addressing potential errors, response format, or integration with sibling tools, though annotations help fill some gaps.

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?

With 100% schema description coverage, the input schema already documents all 10 parameters thoroughly. The description adds minimal semantic value by mentioning 'HTML and plain text content, CC/BCC, and scheduled sending with natural language times', which loosely maps to parameters like 'html', 'text', 'cc', 'bcc', and 'scheduled_at', but doesn't provide additional details beyond 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?

The description clearly states the action ('Send an email') and specifies the resource ('from your verified domain'), distinguishing it from sibling tools like 'reply_email' or 'send_from_mailbox'. It explicitly mentions key capabilities like HTML/plain text support and scheduled sending, making the purpose specific and well-defined.

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 implies usage for sending emails with scheduling and content options, but does not explicitly state when to use this tool versus alternatives like 'send_from_mailbox' or 'reply_email'. It provides some context (e.g., 'from your verified domain') but lacks clear exclusions or direct comparisons to sibling tools.

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