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

With no annotations, the description carries the full behavioral burden. It does disclose a meaningful operational fact — '5 free trial calls per signed wallet' — implying a paid, wallet-authenticated service with rate limits. But it says nothing about return format, error behavior, or query semantics, leaving the safety/cost profile only partially covered.

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 short and reads quickly, but the 'x402-dns:' prefix merely restates the tool name, and the emoji plus trial-call note crowd out more useful content. It is terse without being informative.

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?

No annotations, no output schema, and four fully undocumented parameters with none required for a DNS lookup. For a tool this ambiguous, the description should clarify required inputs and expected response, but it omits all of that.

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 0% across four parameters (host, name, types, domain) and the description explains none of them. It never clarifies the relationship between host/name/domain or how 'types' maps to the listed record types, so an agent has no guidance on which field to populate.

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 names the resource (DNS) implicitly through the tool name and lists the queryable record types (A, AAAA, MX, TXT, NS, CNAME), from which a lookup action can be inferred. However, there is no explicit verb, and it does nothing to distinguish itself from the many overlapping siblings such as x402-dns-all, x402-dns-lookup, x402-dns-record, x402-cname-lookup, or x402-mx-lookup.

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?

There is no statement of when to use this tool versus the numerous DNS siblings. The record-type list hints at what it queries but gives no context, conditions, or exclusions, leaving the agent to guess whether this is the general lookup or a record-specific one.

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