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

Annotations already cover read-only, non-destructive, open-world and non-idempotent, and the description adds context beyond them: the DoH provider, per-call pricing via x402 USDC or card key, first 25 free, failed calls free, and the warning that repeats are not free (consistent with idempotentHint=false). It also discloses what is returned: TTL per answer, response code (NOERROR/NXDOMAIN) and DNSSEC validation status.

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?

Purpose and record list are front-loaded, followed by use cases, then operational details. It is dense and every clause adds information, though the pricing parenthetical ('$0.002/call via x402 USDC or a card key (/credits), first 25 free; failed calls free') is somewhat cluttered.

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?

Despite no output schema, the description names the returned fields (TTL, response code, DNSSEC status), and for a two-parameter read-only lookup it covers cost, auth mechanism, and failure behavior. An agent has everything needed to call it correctly.

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%, so the schema already documents name (including the URL-host behavior) and type with its full record list and default. The description only adds a usage example (name=example.com) and the default of A, so it does little beyond what the schema provides.

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?

States a specific verb and resource ('Look up DNS records of a domain') and enumerates the supported record types, plus the transport (DNS-over-HTTPS, Cloudflare 1.1.1.1). It is clearly distinguishable from siblings like dns_propagation, which it names.

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?

Gives concrete when-to-use scenarios (check email via MX/SPF, verify a domain, debug a DNS change) and explicitly routes propagation checks to dns_propagation. That is an explicit alternative with a stated selection condition.

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