SiteCheck Web Intel

Reports whether Shodan's pre-collected passive scan data

security_open_resolver_check

Read-only

Reports whether Shodan's pre-collected passive scan data shows TCP port 53 (DNS) open on an IPv4 address. It is a passive port fact only: it does not send a query, so it cannot say whether the server answers recursively for outside names. Absence means not seen, not closed. Related tools on this server, for a different need: security_open_port_scanner when you need to list the TCP ports Shodan has seen open on an IPv4. Price: $0.002 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

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": {
      "ip": "<ip>"
    },
    "name": "security_open_resolver_check"
  }
}

Input Schema

Name	Required	Description	Default
`ip`	Yes	IPv4 address such as 8.8.8.8 (required)

Output Schema

Name	Required	Description	Default
`ip`	No
`known`	No
`source`	No
`checkedAt`	No
`dnsPortSeenOpen`	No
`recursionTested`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 23, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Goes well beyond the readOnlyHint/openWorldHint annotations: it discloses that no query is sent, that absence means 'not seen' rather than 'closed', and that only confirmed-open evidence is returned. It also states the billing model ($0.002 USDC per successful call via x402, failed calls uncharged), which is behavior an agent cannot learn from annotations or schema.

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?

Front-loads the capability, then the caveat, then the alternative, then pricing — a logical order. Every sentence carries information, though the payment/pricing sentence is long and could be trimmed without losing the key fact that failed calls are free.

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?

For a single-parameter lookup with an output schema, the description supplies everything an agent needs: exact semantic scope, the meaning of an empty result, the limitation on recursion testing, an alternative tool, and cost. No material gap remains for correct invocation or interpretation.

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

Parameters3/5

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

Schema coverage is 100%, with the single `ip` parameter already documented as an IPv4 address with an example. The description adds only the implicit constraint that the address is IPv4 (not hostname or IPv6), duplicating rather than extending the schema, so baseline 3 applies.

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: reports whether Shodan's passive scan data shows TCP/53 open on an IPv4 address. It also scopes the claim precisely ('a passive port fact only') so the agent understands this is a data lookup, not a live resolver interrogation, and it differentiates itself from security_open_port_scanner by name.

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

Usage Guidelines4/5

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

Explicitly routes the agent to a sibling: use security_open_port_scanner when you need the full list of TCP ports Shodan has seen open. It also sets a clear negative boundary (it cannot answer recursion behavior). It lacks an explicit 'use this tool when…' clause, so the positive trigger is inferred from the purpose sentence rather than stated.

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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