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

With no annotations, the description carries the full burden and does so: it declares read-only, states it reads resolvers' views and never queries the target host, and previews the return shape (per-resolver record set and DNS status, an agreement flag, and a note). This is unusually rich behavioral disclosure for a no-annotation tool.

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?

Front-loaded with the core action, then the interpretation rules. The geoBalanced/anycast explanation is a long clause, but it earns its place by preventing a false divergence alarm; overall it is dense rather than padded.

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?

There is no output schema, so the description must and does describe the return payload. Combined with the read-only statement, the never-queries-host constraint, and the interpretation guidance, nothing essential for correct invocation is missing.

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% with only two params, so the schema already documents both. The listed record types and the default of A merely mirror the schema, adding no new syntax or format detail; baseline 3 applies when the schema does the heavy lifting.

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 — querying several named public resolvers over DNS-over-HTTPS and comparing their answers. The multi-resolver comparison scope inherently differentiates it from single-resolver siblings like dns_lookup and reverse_dns, so an agent can route correctly without opening the schema.

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?

Explains what a result means in practice: agreement is normal, divergence signals propagation/stale cache/split-horizon, and the geoBalanced shared-ASN case is expected CDN behavior. That gives clear diagnostic context for when to reach for this tool, but it never names an alternative tool or an explicit when-not condition.

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