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

Annotations already declare readOnly, idempotent, non-destructive. Description adds details on which records are returned and cost, but doesn't mention any potential rate limits or side effects. Adds useful context beyond 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?

Two sentences plus a brief cost example. Front-loaded with most important information (record types). Every sentence serves a purpose with no waste.

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 output schema exists, return values are covered. Description fully explains what records are returned, use case, and cost. Completely adequate for a simple DNS lookup tool.

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 covers the single parameter 'domain' with description. Description reinforces with an example ('?domain=example.com') but doesn't add new meaning beyond what schema provides. Schema coverage is 100%.

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 exact record types (A/AAAA/CNAME, MX, NS, TXT, SOA, SPF, DMARC, DKIM) making it clear what the tool does. This distinguishes it from sibling tools like get_ping or get_seo_* which serve different purposes.

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?

Explicitly states the tool is for 'deliverability, security, and research agents,' providing context. Does not mention when not to use it, but given its narrow focus, alternatives are implied by other tools.

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