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

No annotations are supplied, so the description carries the full burden. It discloses pricing ($0.01/call), a free-trial allowance for a signed wallet, and the shape of the returned data, which is real value. It says nothing about failure behavior for unresolvable domains, timeouts, or unreachable hosts, which matters for a network-facing 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 first two sentences are tight and front-loaded with the payload description. The trial allowance is then stated twice ('5 free trials' and '🆓 5 free trial calls per signed wallet'), which is redundant padding in an already short description.

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 this covers the essentials: what is checked, what comes back, and the cost model. The gaps are the input format for 'domain' and the absence of any error/timeout expectations, which are the two things an agent most needs before invoking a live web check.

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?

There is a single 'domain' parameter with 0% schema description coverage, and the schema even lists required parameters as zero. The description never clarifies whether the value should be a bare hostname, a full URL, or accept a scheme/subdomain, so the agent's only parameter must be guessed.

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?

The description names a concrete verb and resource ('Combined domain check') and enumerates the two outputs: SSL cert validity (issuer, expiry, days remaining) and HTTP headers. 'Two checks, one call' distinguishes it from single-purpose siblings like x402-ssl-check, x402-cert-expiry and x402-http-headers, though the tool name 'domain-intel' alone would have been opaque.

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?

Usage is only implied: the agent can infer this is a bundled alternative to calling the SSL and header tools separately. The description never explicitly says when to prefer this over x402-ssl-check or x402-http-headers, nor any prerequisites such as the target being reachable over HTTPS.

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