search_dns

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

With no annotations, the description carries the full burden and does it well: it discloses that no external API or credentials are needed, that lookups go through the resolver so the target sees the resolver rather than the caller, and that DKIM selector probing is conditional on active tools. It stops short of rate-limit or failure behavior, but the operational profile is unusually well communicated.

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?

Four tight sentences, front-loaded with the enumeration scope and then the email-security value, followed by the passive-mode caveat. The bracketed active-tools note is dense but earns its place; nothing is redundant.

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 two-parameter read-only lookup with no output schema and no annotations, the description covers what is enumerated, the specific misconfigurations it detects, and the passive/probing behavior. Only the shape of returned findings and the domain-parameter expectations are left implicit.

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?

Two parameters at 50% coverage: json_output is documented in the schema while domain is not. The description implies a domain target and JSON result framing but adds no syntax, TLD, or selector-format detail beyond the schema, so it neither compensates for nor improves on the structured fields.

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 a specific verb (enumerate) and resource (DNS records), then enumerates the exact record types it returns (A, AAAA, MX, NS, TXT, CNAME, SOA) and adds the email-security angle. This is unambiguous and clearly distinct from the IP/WHOIS/RDAP siblings.

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 implied by the enumeration scope and the note that DKIM selector probes only run with active tools enabled, but there is no explicit guidance on when to reach for this versus search_whois, search_rdap, or search_ip. The agent must infer when DNS enumeration is the right first step.

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