Historical DNS records

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, covering the safety profile. The description adds a meaningful behavioral detail: the output includes the date range each value was observed, which goes beyond what annotations provide. No contradiction exists.

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 two sentences with zero waste. The core action is front-loaded in the first sentence, and the use case is stated efficiently in the second. Every word earns its place.

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?

The description explains what the tool does and its primary use case. The schema covers all parameters including pagination and response format. While there is no output schema, the response_format parameter lets the agent choose between markdown and JSON, and the description notes the date-range detail. For a read-only tool with clear parameters, this is adequately complete.

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 covers 100% of parameters with descriptions, including enums for type and response_format, page bounds, and domain pattern. The description adds no extra parameter semantics beyond what the schema already provides, so the baseline of 3 is appropriate.

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 retrieves historical DNS record values for a domain, including the date range each value was observed. It explicitly names the resource (DNS history) and distinguishes it from siblings by focusing on DNS rather than whois, subdomains, or other data types, and adds a specific use case (spotting infrastructure migrations and origin IPs predating CDN).

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 gives a concrete use case ('primary tool for spotting infrastructure migrations and origin IPs that predate a CDN'), telling when to use it. It does not explicitly contrast with sibling tools, but the name and description make it clear it's for DNS history rather than whois, subdomains, or other securitytrails tools, so context is strong but not fully explicit.

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