check_ns

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds real value beyond that by disclosing conditional behavior ('when the infrastructure probe is available') and the scope of what is compared (parent vs child NS sets, AA responses, glue), which an agent could not infer from annotations alone.

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 compact sentences with the core action and scope front-loaded and no filler. The dense enumeration of checks is informative rather than redundant, though the sentence could be marginally tighter.

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?

With an output schema present, return values need not be explained, and annotations cover safety and idempotency. The description covers what, why, and workflow placement; the only gap is a slightly vague dependency on 'the infrastructure probe' without stating the fallback behavior when unavailable.

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%, so all three parameters (domain, format, force_refresh) are already documented in the schema, and the description adds no syntax or format detail. Baseline 3 applies when the schema carries the parameter burden.

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 ('Audit a domain's nameserver delegation and redundancy') and then enumerates the concrete checks performed: provider identification, parent/child NS comparison, AA response verification, and glue address checks. This is clearly distinguishable from siblings like check_authoritative_dns_infra or check_root_server_set.

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 explicit use cases ('detect stale registrar delegations, lame nameservers, and intermittent resolution risk') and situates the tool within the scan_domain audit workflow. It stops short of naming when to prefer an alternative sibling or stating exclusions, so it is not a full 5.

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