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

Annotations already declare readOnly, idempotent, openWorld, non-destructive; the description adds genuinely new behavioral facts: cost of $0.005 USDC per successful call via x402 on Solana, and that the same tool is reachable over HTTPS at a specific URL. It also indicates the output is a scored result with actionable issues. No auth/rate-limit notes beyond the payment model, and no failure/refund semantics.

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?

Dense but front-loaded: capability list first, use case second, pricing/endpoint last. Every clause carries information, though the record-type enumeration is packed into one long sentence.

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?

No output schema exists, so the description must convey what comes back — it does so by listing the record types inspected and stating results are 'scored with actionable issues'. It stops short of describing the response shape (score range, per-check structure), but is sufficient to select and call the tool.

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?

Single required parameter with 100% schema description coverage ('Domain name, e.g. example.com'), so the schema carries the semantics. The description does not clarify edge cases such as subdomains, IDN, or whether bare domains without scheme 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?

Starts with a specific verb+resource ('Email authentication & deliverability posture for a domain') and enumerates the concrete checks (SPF qualifier/lookup count/duplicates, DMARC policy/rua/pct, DKIM selectors, MTA-STS, TLS-RPT, BIMI, MX). This makes it distinguishable from plain MX/DNS tools, though it never names a sibling explicitly.

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?

'Useful for spoofing-risk and vendor checks' hints at context but gives no explicit when-to-use versus email_validate, mx_check, dns_dump, or phishing_score. The agent must infer that this is the multi-record, scored posture check rather than a single-record validator.

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