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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior; the description adds useful context beyond those: 'Single HTTP GET, no auth, no destructive actions,' plus the internal chain-walking and signature-checking behavior. It does not contradict 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?

Every sentence earns its place: purpose, validation behavior, return contents, usage guidance, and protocol-level details. It is compact, front-loaded, and free of filler.

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 one-parameter tool with no output schema, the description is complete: it explains what is validated, how it behaves, what it returns (chain steps, algorithm grades, boolean valid), and when to choose it over an alternative. No significant context gap remains.

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 single parameter has full schema coverage with a clear description ('Domain name only, e.g. example.com (no URL, path, or port)'), so the description need not add much. It reinforces the semantic by saying validation applies when the domain claims DNSSEC, but adds no additional syntactic or formatting detail beyond the schema.

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?

Description specifies a clear verb+resource ('Read-only DNSSEC chain validation') and details the validation process: walks DS/DNSKEY chain, checks signatures, algorithm strength, key rollover state. It also distinguishes itself from sibling lookup_dns by noting that tool is for raw key data only.

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?

Explicit guidance is provided: 'Use when a domain claims DNSSEC; use lookup_dns(type='DNSKEY') for raw key data only.' This directly states when to invoke this tool and names the relevant alternative.

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