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 mentions the tool checks availability and returns prices, but lacks critical details: whether it's a read-only operation, if it requires authentication, rate limits, error handling, or the exact response format. For a tool with 7 parameters and no annotations, this leaves significant gaps in understanding its behavior and constraints.

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 and front-loaded, with three sentences that efficiently convey the core functionality. The first sentence states the purpose, the second adds context and benefits, and the third is a call-to-action. There's minimal waste, though the last sentence ('Invoke this endpoint.') is slightly redundant but not detrimental.

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 explains what the tool does but fails to address key contextual aspects: how to structure the request (e.g., which parameters to use for domain names and years), what the output looks like, error conditions, or authentication needs. For a tool with this level of complexity, more detail is necessary to be fully actionable.

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 specific parameter information beyond implying domain names and years are involved, but doesn't clarify which parameters correspond to these inputs. Since the schema handles parameter documentation, the baseline score of 3 is appropriate, as the description doesn't add meaningful semantic value beyond what's already structured.

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 tool's purpose: 'check the availability of up to 20 domain names in a single request' and 'determine which domains are available for registration and their corresponding prices'. It specifies the verb ('check'), resource ('domain names'), and scope ('up to 20', 'bulk'). However, it doesn't explicitly differentiate from sibling tools like 'check_domain_availability' or 'check_domain_availability_batch', which appear to serve similar functions.

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 implies usage context with phrases like 'ideal for bulk domain searches' and 'quickly determine', suggesting it's for efficiency when checking multiple domains. However, it doesn't provide explicit guidance on when to use this tool versus alternatives (e.g., 'check_domain_availability' for single domains) or any prerequisites. The guidance is present but not comprehensive.

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