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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does add useful context beyond the schema: the free-trial limit ('🆓 5 free trial calls per registered wallet') and the accepted record types. However, it does not disclose the return format, behavior for nonexistent domains or empty records, or what happens when no 'type' is specified, leaving real gaps for an unannotated tool.

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 short sentences with the core purpose front-loaded. The record-type list earns its place as parameter guidance. The emoji and 'registered wallet' phrasing is slightly promotional but carries real information about usage limits, so it is not wasted space. Minor redundancy ('DNS Lookup:' followed by 'Resolve DNS records') keeps it from a 5.

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 2-param lookup tool with no output schema and no annotations, the description conveys the essential record-type vocabulary and the trial-call constraint. Yet it leaves material ambiguities unanswered: whether a domain is mandatory (schema marks no params required), what the response contains, and whether one type or all listed types are returned per call. This is adequate for a simple lookup but not 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?

Schema coverage is 100%, but both schema descriptions are weak ('Type to process', 'Domain to process'). The tool description adds genuine value by enumerating the acceptable values for the 'type' parameter (A, AAAA, MX, TXT, NS, CNAME, SOA, PTR), effectively supplying the enum list the schema lacks. It does not clarify the oddity that neither parameter is marked required, or what the default behavior is if 'type' is omitted.

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 states a specific verb and resource: 'Resolve DNS records: A, AAAA, MX, TXT, NS, CNAME, SOA, PTR.' The list of supported record types makes the tool's scope concrete and distinguishes it from single-type siblings like x402-cname-lookup or x402-mx-lookup. However, it does not differentiate from overlapping siblings x402-dns, x402-dns-all, and x402-dns-record, so it stops short of a 5.

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?

No guidance is given on when to use this tool versus alternatives. With multiple DNS-related siblings (x402-dns-all, x402-dns-record, x402-dns-reverse, x402-mx-lookup, x402-txt-lookup), the description should say whether this is the general-purpose multi-type lookup or a fallback for the others. No exclusions or conditions are stated.

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