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

The description discloses important behavior beyond the readOnlyHint/openWorldHint annotations: it mentions the $0.01 USDC payment on Base and the payTo address. It also enumerates the data sources, but it does not clarify error cases or whether the payment is external to the MCP request.

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 compact, front-loads the payment requirement, and uses one dense sentence plus the payTo address. There is no filler, repetition, or unnecessary context.

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?

For a single-parameter, read-only tool with no signed output schema, the description provides enough information to choose the tool and invoke it: what data is covered, that payment is required, and the expected input. A brief statement of the response format would have made it fully complete, but the description is adequate.

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 already fully defines the host parameter as a public DNS hostname, not a URL or IP. The tool description adds no new parameter insight; it mostly repeats the same wording. Baseline 3 is appropriate because schema coverage is high.

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 identifies the tool's output: a DNS/RDAP/TLS/SPF/DMARC dossier for a public hostname. It distinguishes the tool's scope from siblings by naming the data sources, but it does not use an explicit verb like 'returns' or explicitly compare it to alternatives.

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?

Usage is implied: call this tool when you need domain-related data from DNS, RDAP, TLS, SPF/DMARC. There is some payment context and a public-hostname constraint, but no explicit guidance about when to prefer another tool or when not to use it.

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