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

No annotations are provided, so the description must carry safety and behavioral disclosures. It only says 'get' (implying read-only) and 'free tool', but doesn't mention rate limits, required permissions, or what exactly the result contains. This is minimal behavioral transparency for a tool with no annotations.

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 the core purpose front-loaded. The second sentence's 'Free tool by Postbox Services' adds trust context but is not essential for invocation, making it slightly less than perfectly lean.

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 tells what it does and why, but for a tool with no output schema and no annotations, it omits details like result format, safety profile, and when not to use it. It's adequate for a simple lookup but leaves an agent to infer several operational aspects.

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 schema already documents the only parameter (domain) with 100% coverage, so the description doesn't need to add much. It adds no extra semantics beyond what the schema provides, matching the baseline for high schema description 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 tool retrieves a domain's registration date and age, a specific verb and resource. It adds context about sending reputation, but doesn't explicitly distinguish it from the sibling whois_lookup, which may also return registration data.

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 for evaluating sending reputation ('young domains have weak sending reputation'), but doesn't explicitly state when to prefer this over alternatives like whois_lookup or provide exclusions. The context is helpful but not explicit guidance.

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