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

Annotations already cover read-only, idempotent, open-world and non-destructive traits, so the description only needs to add context. It does so meaningfully by disclosing the exact resolver set queried and the cost/rate-limit model (10 free calls/day, then $0.002 via HTTP endpoint or X-API-Key credits), which the agent cannot get from annotations. It omits timing/timeout behavior, which is relevant for a propagation check.

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?

The purpose and the six resolvers are front-loaded in one compact sentence, followed by pricing. Nothing is padding, though the pricing clause mixes in an HTTP-endpoint mention that is marginal for an MCP caller.

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 tool with a full output schema and complete annotations, the description covers purpose, scope of resolvers, and cost. Return-value shape is handled by the output schema; only propagation-timing expectations are left unexplained.

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% and both parameters (domain, type with its record-type list) are already documented in the schema. The description adds no format, defaulting, or constraint information beyond that, so the baseline of 3 applies.

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 6 public resolvers... compare answers') and even names the resolvers, so the agent knows exactly what is being checked. It never names the sibling dns_lookup, which is the obvious alternative for a single-resolver query, so the differentiation is only implicit.

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?

The framing question 'has my DNS change propagated?' implies the usage scenario (post-change verification) but does not state when to prefer this over dns_lookup or when it is unnecessary. Usage is inferred rather than instructed.

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