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

Goes well beyond the readOnly/idempotent/non-destructive annotations by disclosing commercial terms (EUR 99 net per domain), the non-binding nature of the quote, and the absence of side effects ('creates no order, contract or payment and stores nothing'). The openWorldHint annotation is consistent with an external DNS/email-authentication lookup, and the description adds the crucial guarantee that nothing is persisted.

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-loads what the tool does, then the output contents, then the no-side-effects guarantee, then the follow-up instruction. Every clause carries information an agent needs; no filler or repetition of the name/title.

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 no output schema, the description still enumerates the return payload (price, scope, acceptance criteria, baseline) and explains what the caller must retain for the later verification step. For a single-parameter read-only tool, nothing an agent needs in order to call it or chain it correctly 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?

Only one parameter, and the schema already documents it at 100% coverage with an example ('example.com'). The description adds the meaningful constraint that exactly one domain is checked per call, but nothing beyond that about format or normalization rules, so this sits at the baseline.

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 ('Runs the email-authentication check of one domain and returns ... a quote for Fix & Verify') plus the concrete contents of the output (price, scope, acceptance criteria, baseline). It is clearly separable from the sibling verifyFixVerify, which it explicitly names as the follow-up step.

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 clear sequencing guidance: call this first to obtain the quote, keep the criteria and baseline, then call verifyFixVerify after the DNS records are published. It does not address when to prefer the other sibling, checkDomain, or whether a prior check is a prerequisite, so the alternative-selection guidance is incomplete.

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