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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so safety is covered. The description adds nothing beyond that – no note on which resolver is used, propagation/caching behavior, timeouts, or failure handling for NXDOMAIN – so it contributes no behavioral context of its own.

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?

A single efficient sentence, front-loaded with the verb and resource. It is tight, though the record-type enumeration is largely duplicated by the schema's type parameter.

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?

A simple two-parameter read tool with full schema and annotations, so most of what an agent needs is present. But with no output schema, the description does not say anything about the shape of the response (per-record values, empty results), leaving a real gap.

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 description coverage is 100%, including the note that type defaults to MX. The description's record-type list is redundant with the schema, so the baseline 3 applies with no added meaning.

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 (query DNS records for a domain) and enumerates the supported record types, which tells an agent this is the generic DNS lookup. It does not, however, distinguish itself from specialized siblings like lookup_mx, lookup_txt, or check_cname.

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 phrase 'any DNS record type' suggests it is the general-purpose option versus the targeted sibling checks. There is no explicit when-to-use/when-not and no mention of which sibling to prefer for a single record type, nor any prerequisites.

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