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

With no annotations, the description carries the full burden and does disclose real behavioral traits: primary and fallback resolvers, rejection of IP literals and private names, and a per-call price of $0.002 billed through x402. It omits rate limits, failure/error behavior, and the shape of the response.

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?

Three tight sentences: capability first, input constraints second, cost last. Every clause earns its place and nothing is repeated.

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 simple stateless lookup with no output schema and no annotations, the description covers provider, valid input domain, and pricing — the things an agent needs before calling. The notable gap is that nothing describes the returned record structure, which the absent output schema would otherwise require.

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 67%, so the baseline is 3. The record-type list in the description duplicates the schema enum and the 'name' description already says 'Hostname to look up', so no meaning is added beyond what the schema provides; the optional idempotency key is documented only in the schema.

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?

Names a specific verb and resource (DNS-over-HTTPS lookup) and enumerates the record types returned, plus the upstream resolvers. It is clearly a DNS query tool rather than a validator, but it never distinguishes itself from the sibling name_resolve, which could plausibly overlap.

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: the input-domain constraints ('Rejects IP literals and private names') tell the agent what will fail, but there is no explicit statement of when to pick this over name_resolve or address_validate.

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