Zapmail MCP Server

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

No annotations are provided, so the description carries full burden. It mentions this is an 'endpoint' but doesn't disclose whether this is a read or write operation, what permissions are needed, whether it's idempotent, what happens on success/failure, or any rate limits. 'Assign new mailboxes' implies a write operation but lacks crucial behavioral details.

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 very concise with only two short sentences. However, the second sentence 'Invoke this endpoint' adds minimal value and could be considered redundant. The structure is front-loaded with the core purpose first.

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 tool with 7 parameters, no annotations, no output schema, and complex sibling relationships, the description is inadequate. It doesn't explain what the tool returns, what 'assign' means operationally, or provide any context about the domain/mailbox relationship. The 100% schema coverage helps with parameters but doesn't compensate for missing behavioral and contextual information.

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%, so the schema fully documents all 7 parameters. The description adds no parameter-specific information beyond what's in the schema. The baseline is 3 when schema does the heavy lifting, even though the description provides zero 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 'assign new mailboxes to specific domains' which is a tautology of the tool name/title 'Assign New Mailboxes to Domains'. It doesn't provide any additional specificity about what 'assign' means operationally or how this differs from similar sibling tools like 'assign_prewarmed_mailboxes_25774338e0' or 'create_mailboxes_for_zero_domains'.

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 no guidance on when to use this tool versus alternatives. It simply says 'Invoke this endpoint' without any context about prerequisites, appropriate scenarios, or distinctions from the many sibling tools related to mailboxes and domains in the list.

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