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

No annotations exist, so the description carries the whole burden. It does disclose valuable behavior: the check set, that results include issues and a score, and an explicit price of $0.001 USDC (a real cost/auth constraint an agent must know before calling). It does not state read-only safety, rate limits, timeouts, or what the score means or its range.

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 use case, then the check inventory, then the value proposition, then an example and price — a sensible ordering in a very short space. The telegraphic phrasing ('issues + score', 'Structured JSON beats shell dig/openssl') trades a little readability for density but wastes no sentences.

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 one-parameter, no-output-schema tool, the description covers what is checked, roughly what comes back (issues + score), the input format via example, and the cost. The remaining gap is the score's semantics and the response shape, which are minor given the tool's simplicity but would help an agent interpret results.

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 0% and the single property is an undescribed string, so the description must compensate — and it does with the example {domain:"stripe.com"}, which signals a bare hostname with no scheme or path. That is meaningful disambiguation the schema does not provide, though it stops short of stating whether subdomains or ports are accepted.

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 ('check domain health') and then enumerates the exact dimensions covered: DNS via DoH, DNSSEC, TLS/HTTPS, HSTS, MX/SPF/DMARC, plus an aggregate issues list and score. None of the siblings (company_research, read_url, extract_links) overlap with this scope, so an agent can route to it without ambiguity.

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 a concrete triggering context ('when vetting domain health before outreach') and positions itself against a non-MCP alternative (shell dig/openssl), which is useful framing. It does not name any sibling tool or state when-not to use it, so it stops short of full routing guidance.

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