Zapmail 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. It discloses key behavioral traits: it's a purchase operation (implies mutation and payment), uses wallet funds preferentially, and may return a payment link. However, it lacks details on permissions, error conditions, rate limits, or what happens after purchase (e.g., domain activation).

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 a single, efficient sentence that front-loads the core purpose and adds critical behavioral context without any wasted words. Every part of the sentence earns its place by informing the agent's decision-making.

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 (financial transaction with multiple parameters) and lack of annotations and output schema, the description is adequate but incomplete. It covers the main action and payment behavior but omits details on return values, error handling, and post-purchase outcomes, which are important for a purchase tool.

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 already documents all parameters thoroughly. The description does not add any meaning beyond what the schema provides (e.g., it doesn't explain domain format constraints or payment link specifics), meeting the baseline for high coverage.

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 specific action ('Purchase') and resource ('one or more domains'), and distinguishes itself from siblings by focusing on the purchase transaction rather than domain management, configuration, or availability checks. It adds nuance with the wallet-first behavior.

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 clear context about when to use it (to purchase domains) and implies an alternative outcome (payment link if wallet funds are insufficient), but does not explicitly name when not to use it or compare it to sibling tools like 'check_domain_availability' or 'purchase_subscription'.

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