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 of behavioral disclosure. It describes what the tool retrieves (aged/high-reputation domains) but lacks critical behavioral details: it doesn't mention whether this is a read-only operation, what authentication might be required, whether there are rate limits or costs, what the return format looks like (e.g., pagination, fields), or potential side effects. The phrase 'Invoke this endpoint' adds no meaningful behavioral context.

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 appropriately concise with three sentences that efficiently convey the core purpose and domain characteristics. The first sentence states the main action, the second elaborates on domain quality, and the third is a redundant call-to-action ('Invoke this endpoint') that could be omitted without loss. Overall, it's well-structured and front-loaded with key information.

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 (7 parameters, no annotations, no output schema), the description is incomplete. It adequately explains what domains are retrieved but fails to address critical contextual aspects: no behavioral transparency (e.g., safety, auth), no usage guidelines versus siblings, and no details on output format or pagination. For a tool with many parameters and no structured safety hints, this leaves significant gaps for 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?

The input schema has 100% description coverage, providing clear documentation for all 7 parameters (e.g., method override, path override, query parameters). The description adds no parameter-specific information beyond what's in the schema—it doesn't explain which parameters are relevant for this specific endpoint or provide usage examples. With high schema coverage, the baseline score of 3 is appropriate as the schema handles parameter documentation adequately.

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 verb ('Retrieve') and resource ('list of available aged/high-reputation domains from the marketplace'), specifying they are premium domains with established history, age, and quality metrics. It distinguishes itself from siblings like 'get_available_domains_for_registration_13521189e0' by focusing on aged/reputation domains rather than registration availability, but doesn't explicitly contrast with all similar tools like 'list_domains' or 'retrieve_all_domains_13520015e0'.

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 mentions 'aged/high-reputation domains' but doesn't specify scenarios where this is preferred over other domain-related tools like 'get_available_domains_for_registration_13521189e0' (for new domains) or 'list_domains' (general listing). No prerequisites, exclusions, or explicit alternatives are stated.

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