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 mentions payment deduction from the wallet, which is a key financial implication, but lacks details on permissions required, rate limits, whether purchases are reversible, or what happens on failure. The description adds some context but is insufficient for a mutation tool with zero annotation coverage.

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 that directly state the tool's function and a key behavioral note (payment deduction). It is front-loaded with the main purpose, though the second sentence ('Invoke this endpoint.') is redundant and adds no value, slightly reducing efficiency.

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 (purchasing domains, a financial transaction), lack of annotations, and no output schema, the description is incomplete. It misses critical details like response format, error handling, or confirmation of purchase success, making it inadequate for safe and effective use by an AI agent.

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 input schema already documents all 7 parameters (e.g., method, path, body). The description does not add any meaning beyond the schema, such as explaining which parameters are relevant for purchasing domains or how to structure the body. Baseline 3 is appropriate as the schema handles parameter documentation.

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 action ('Purchase') and resource ('aged/high-reputation domains from the marketplace'), making the purpose specific and understandable. However, it does not explicitly differentiate from sibling tools like 'purchase_domains' or 'purchase_prewarmed_subscription_25774263e0', which likely handle different types of domain purchases, leaving some ambiguity in sibling distinction.

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 mentions that payment is deducted from the wallet balance, implying a prerequisite (sufficient funds), but provides no explicit guidance on when to use this tool versus alternatives like 'purchase_domains' or 'purchase_prewarmed_subscription_25774263e0'. There are no clear exclusions or named alternatives, leaving usage context vague.

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