Inbound Email MCP Server

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

Annotations already provide readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering safety and idempotency. The description adds context about what data is returned (content, headers, attachments, status), which is useful behavioral information beyond annotations. However, it doesn't disclose potential limitations like rate limits, authentication needs, or error conditions.

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 conveys the tool's purpose and scope. It's front-loaded with the core action ('Get detailed information about a specific email') and adds specific details without redundancy. Every word earns its place.

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 read-only, idempotent tool with one well-documented parameter and no output schema, the description provides adequate context about what data is returned. It covers the key aspects of the tool's behavior. However, without an output schema, it could benefit from more detail on return format or error handling, but it's largely complete for its complexity.

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 the single parameter 'id' fully documented in the schema. The description doesn't add any parameter-specific information beyond what the schema provides (e.g., no examples of valid IDs beyond the schema's 'email_xxx' example). Baseline 3 is appropriate when the schema carries the full parameter documentation burden.

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 ('Get') and resource ('email') with specific details about what information is retrieved ('detailed information including full content, headers, attachments, and delivery status'). It distinguishes from siblings like 'list_emails' (which lists emails) and 'get_thread' (which retrieves threads rather than individual emails).

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 context by specifying 'a specific email' and the need for an email ID, which suggests it's for retrieving details of known emails. However, it doesn't explicitly state when to use this vs. alternatives like 'list_emails' for browsing or 'get_thread' for thread-level details, nor does it mention prerequisites or exclusions.

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