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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful behavior not in annotations — a 6-credit cost and a plan-tier gating note — but the plan note ('paid plans add TXT, CNAME, and nameserver records') conflicts with the schema, which lists CNAME, NS, and TXT among the default set, leaving the agent unsure which is accurate.

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 efficient sentences with the capability front-loaded and cost at the end. The leading 'DNS Lookup: DNS Lookup retrieves' redundantly restates the tool name and title, which is minor wasted space in an otherwise tight definition.

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?

This is a simple two-parameter read tool with full schema coverage, an output schema, and read-only annotations, so most of the burden is already carried elsewhere. The description covers purpose and cost but undercuts itself with plan-tier claims that contradict the default record set, which is the one thing an agent would need resolved before choosing record types.

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?

With 100% schema description coverage, the schema already fully documents both parameters, including the default record-type list and the opt-in types. The description restates some record types as prose but adds no formatting or syntax guidance for the comma-separated 'type' value, so baseline 3 applies.

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 uses a specific verb and resource — 'retrieves published DNS records for any domain' — and enumerates the record families covered (A, AAAA, MX). It does not, however, distinguish itself from nearby siblings such as MXLookup, Nameservers, or ReverseDNSLookup, so an agent must infer that this is the general-purpose entry point.

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 only implied: 'any domain' suggests a general lookup, and the mention of specific record types hints at breadth, but there is no explicit statement of when to choose this over MXLookup or Nameservers. No prerequisites, rate-limit context, or exclusion conditions are given beyond the credit cost.

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