Email SMTP/IMAP MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions 'flexible filters' and optional content/attachments but doesn't cover critical aspects like whether this is a read-only operation, potential rate limits, authentication needs, or what the return format looks like (e.g., list structure, pagination). For a search tool with 6 parameters, this leaves significant gaps.

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 concise and front-loaded, with the core purpose stated in the first sentence. The second sentence adds usage examples without redundancy. However, the examples could be more tightly integrated, and there's room to eliminate minor wordiness (e.g., 'Use this to' is slightly verbose).

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 complexity (6 parameters, nested objects) and lack of annotations and output schema, the description is incomplete. It doesn't explain return values, error conditions, or behavioral constraints, which are crucial for a search tool with filtering options. The agent would struggle to use this effectively without guessing at missing context.

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 description adds minimal parameter semantics beyond the schema, which has 100% coverage. It mentions 'flexible filters' and 'optionally get full email content and attachments,' hinting at the 'filters,' 'include_content,' and 'include_attachments' parameters, but doesn't provide additional context like search syntax or performance implications. Given the high schema coverage, the baseline of 3 is appropriate.

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 tool's purpose as 'Search for emails in your inbox with flexible filters' and mentions 'find specific emails, check for unread messages, or browse your inbox.' It specifies the verb (search/find) and resource (emails/inbox) but doesn't explicitly differentiate from sibling tools like 'emails_modify' or 'folders_list' beyond the search focus.

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 implied usage through examples ('find specific emails, check for unread messages, or browse your inbox') but lacks explicit guidance on when to use this tool versus alternatives like 'email_respond' or 'email_send.' It doesn't mention prerequisites or exclusions, leaving the agent to infer context.

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