WhoisFreaks

SSL certificate lookup

sslLookup

Read-onlyIdempotent

Get the SSL/TLS certificate a domain currently serves, fetched live. Use this to check expiry dates, the issuer, covered hostnames (SANs) or key type, or to debug HTTPS errors. Set chain=true to include intermediate and root certificates when diagnosing trust-chain problems, and sslRaw=true only when you need the raw OpenSSL output, which is long. For DNS records use dnsLookup; for domain ownership use liveWhoisLookup; for an overall risk verdict on the domain use domainReputation. Costs 1 credit, plus 1 credit per 2 certificates with chain=true. Returns each certificate's subject (common name, organisation), issuer, validity dates, serial number, signature algorithm, key algorithm and size, and extensions: covered hostnames (SANs), key usages, issuer and OCSP URLs, and certificate policies. A domain with no certificate returns a "no data found" (HTTP 404) message. Behavior: read-only. Makes one request to the WhoisFreaks API using your WhoisFreaks API key (the WHOISFREAKS_API_KEY environment variable, or on the hosted server the key sent with the request) and uses that account's API credits; nothing is created or changed. If the call fails, the result is a short message instead of data, for example: key invalid, or plan or credits used up (HTTP 401), domain extension not supported (HTTP 403), no data found (HTTP 404), or rate limit reached (HTTP 429).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "domainName": "<domainName>"
    },
    "name": "sslLookup"
  }
}

Input Schema

Name	Required	Description
`chain`	No	If true, return the full certificate chain (end-user certificate through intermediate CA to root CA). Default: false
`format`	No	Response format. Default: json
`sslRaw`	No	If true, include the raw OpenSSL response in the output. Default: false
`domainName`	Yes	Domain name to retrieve SSL certificate for. Accepts: example.com \| https://example.com \| http://example.com

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 13, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations already declare read-only, idempotent, non-destructive and open-world, and the description adds material context they cannot carry: the credit cost model (1 credit, plus 1 per 2 certs with chain), the auth requirement (WHOISFREAKS_API_KEY or hosted-server key), and the concrete failure modes with HTTP codes (401, 403, 404, 429). It also states that failures return a short message rather than data, which shapes how an agent should interpret results.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose, usage, flags, cost, return shape and error behavior are front-loaded in that order, so an agent can stop reading early. It runs long, and the enumerated HTTP error list and full return-field inventory are slightly verbose, though each item is genuinely actionable.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description carries the burden itself and does so: it enumerates the returned fields (subject, issuer, validity, serial, signature and key algorithms, SANs, key usages, OCSP/issuer URLs, policies) and covers the empty-result case. Nothing needed to invoke or interpret the call is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description goes beyond the schema by tying chain=true to billing cost and to the specific diagnostic scenario (trust-chain problems), and by warning that sslRaw output is long. The format enum is left to the schema, which is acceptable since it is self-documenting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Get the SSL/TLS certificate a domain currently serves, fetched live') and immediately contrasts it with the neighboring tools dnsLookup, liveWhoisLookup and domainReputation. An agent can distinguish this from every plausible sibling without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit use cases (expiry, issuer, SANs, key type, HTTPS debugging) and explicit routing rules to alternatives for DNS, ownership and reputation queries. It also conditions the optional flags: chain=true for trust-chain diagnosis, sslRaw=true only when raw OpenSSL output is truly needed.

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

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