Zapmail MCP Server

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

No annotations are provided, so the description must fully disclose behavioral traits. It only states that the tool 'provides a list,' implying a read-only operation, but does not cover important aspects like authentication requirements, rate limits, pagination, or error handling. For a tool with 7 parameters and no annotations, this is insufficient to inform the agent about its behavior beyond basic functionality.

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 with two sentences, front-loading the main purpose. However, the second sentence 'Invoke this endpoint' is redundant and adds no value, slightly reducing efficiency. Overall, it is appropriately sized but could be more streamlined by removing unnecessary phrasing.

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 of 7 parameters, no annotations, and no output schema, the description is incomplete. It does not explain the return format, error conditions, or how parameters influence the list of assignable domains. For a tool with rich input options and no structured output information, the description lacks necessary contextual details to guide effective use.

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 input schema has 100% description coverage, so the baseline score is 3. The tool description does not add any meaning beyond what the schema provides, as it does not explain how parameters like 'method' or 'serviceProvider' affect the domain listing. With 7 parameters fully documented in the schema, the description offers no additional parameter 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 states the tool 'provides a list of domains to which you can assign mailboxes,' which clearly indicates its purpose as a read operation. However, it does not differentiate itself from sibling tools like 'retrieve_all_domains' or 'get_available_domains,' making it vague in comparison. The verb 'provides' is somewhat generic, lacking specificity in how it differs from other domain-listing tools.

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 offers no guidance on when to use this tool versus alternatives. It does not mention any prerequisites, such as needing specific permissions or workspace context, nor does it suggest other tools for related tasks. The sibling list includes multiple domain-related tools, but this description fails to provide any contextual usage information.

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