Zapmail MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions 'Get the payment link... or purchase domains via wallet,' implying a read operation for links and a write operation for purchases, but it doesn't clarify permissions, rate limits, side effects, or response format. This leaves critical behavioral traits unspecified for a tool that may involve financial transactions.

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 brief and front-loaded with the core purpose in the first sentence, followed by a generic endpoint invocation note. It avoids unnecessary details, but the second sentence ('Invoke this endpoint.') adds minimal value, slightly reducing efficiency. Overall, it's appropriately sized with minor redundancy.

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 (7 parameters, potential financial operations) and lack of annotations and output schema, the description is incomplete. It doesn't explain behavioral aspects like authentication needs, error handling, or what the payment link entails, leaving gaps that could hinder an AI agent's ability to use the tool correctly in 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?

Schema description coverage is 100%, so the schema fully documents all 7 parameters. The description adds no parameter-specific information beyond the schema, such as how 'method' or 'path' relate to domain purchases. Since the schema handles parameter documentation adequately, the baseline score of 3 is appropriate, with no extra value from the description.

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 'Get the payment link for a list of domains or purchase domains via wallet,' which clarifies the verb ('Get') and resource ('payment link'), but it's vague about the exact purpose—whether it retrieves links, initiates purchases, or both. It doesn't distinguish from siblings like 'purchase_domains' or 'get_wallet_balance_13490707e0,' leaving ambiguity in scope.

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?

No guidance is provided on when to use this tool versus alternatives. It mentions 'Invoke this endpoint,' but this is generic and doesn't specify prerequisites, context, or exclusions compared to sibling tools such as 'purchase_domains' or 'get_wallet_balance_13490707e0.' The description lacks explicit when/when-not instructions or named alternatives.

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