General Tools

crewofthecaptain.com

Provides general-purpose tools through the Model Context Protocol.

2 endpoints14 known toolsFirst detected October 11, 2026Last detected October 11, 2026

ENDPOINT 1

https://x402-test.crewofthecaptain.com/mcp

No auth detected

MCP server metadata

Name: x402 Format Checker
Version: 1.2.0

Capabilities

tools.listChanged

Server instructions

Format and checksum validation for IBAN, EU VAT, Polish NIP/REGON/PESEL and email, pay-per-call via x402. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. Call list_types (free) first. Paid tools return an x402 payment-required error with requirements; pay with an x402-capable MCP client (payment token in _meta["x402/payment"]). Values are never stored; personal identifiers are masked in results.

Known tools 7

list_types

List the available checks, price, network and payment details (free).

Potential side effects

validate_iban

IBAN: country length + ISO 13616 mod-97 checksum.

Inferred read-only

validate_eu_vat

EU VAT number: per-country format (offline, no VIES); PL also NIP checksum.

Inferred read-only

validate_pl_nip

Polish NIP tax id: 10 digits + weighted mod-11 checksum.

Inferred read-only

validate_pl_regon

Polish REGON: 9 or 14 digits + mod-11 checksum.

Inferred read-only

validate_pl_pesel

Polish PESEL: checksum + encoded birth date and sex.

Inferred read-only

validate_email

Email address syntax (dot-atom local part, LDH domain; no DNS).

Potential side effects

CONNECT WITH APPROVAL

Client installation

Review this server and its permissions before adding it. Secret placeholders must be set locally.

Codex

~/.codex/config.toml

[mcp_servers.x402-format-checker]
url = "https://x402-test.crewofthecaptain.com/mcp"
enabled = true

Claude Code

.mcp.json

{
  "mcpServers": {
    "x402-format-checker": {
      "type": "http",
      "url": "https://x402-test.crewofthecaptain.com/mcp"
    }
  }
}

Claude Desktop

Settings → Connectors → Add custom connector

Name: x402-format-checker
Remote MCP URL: https://x402-test.crewofthecaptain.com/mcp

Add this remote URL as a custom connector in Claude Desktop. Availability depends on the user plan and workspace policy.

Cursor

.cursor/mcp.json

{
  "mcpServers": {
    "x402-format-checker": {
      "url": "https://x402-test.crewofthecaptain.com/mcp"
    }
  }
}

Visual Studio Code

.vscode/mcp.json

Add to Visual Studio Code

{
  "servers": {
    "x402-format-checker": {
      "type": "http",
      "url": "https://x402-test.crewofthecaptain.com/mcp"
    }
  }
}

Generic MCP

Client-specific MCP configuration

{
  "name": "x402-format-checker",
  "transport": "streamable-http",
  "url": "https://x402-test.crewofthecaptain.com/mcp"
}

MCP Inspector

Run the official MCP Inspector locally and enter the indexed Streamable HTTP endpoint.

ENDPOINT 2

https://validate.crewofthecaptain.com/mcp

No auth detected

MCP server metadata

Name: x402 Format Checker
Version: 1.3.0

Capabilities

tools.listChanged

Server instructions

Known tools 7

list_types

List the available checks, price, network and payment details (free).

Potential side effects

validate_iban

IBAN: country length + ISO 13616 mod-97 checksum.

Inferred read-only

validate_eu_vat

EU VAT number: per-country format (offline, no VIES); PL also NIP checksum.

Inferred read-only

validate_pl_nip

Polish NIP tax id: 10 digits + weighted mod-11 checksum.

Inferred read-only

validate_pl_regon

Polish REGON: 9 or 14 digits + mod-11 checksum.

Inferred read-only

validate_pl_pesel

Polish PESEL: checksum + encoded birth date and sex.

Inferred read-only

validate_email

Email address syntax (dot-atom local part, LDH domain; no DNS).

Potential side effects

CONNECT WITH APPROVAL

Client installation

Review this server and its permissions before adding it. Secret placeholders must be set locally.

Codex

~/.codex/config.toml

[mcp_servers.x402-format-checker]
url = "https://validate.crewofthecaptain.com/mcp"
enabled = true

Claude Code

.mcp.json

{
  "mcpServers": {
    "x402-format-checker": {
      "type": "http",
      "url": "https://validate.crewofthecaptain.com/mcp"
    }
  }
}

Claude Desktop

Settings → Connectors → Add custom connector

Name: x402-format-checker
Remote MCP URL: https://validate.crewofthecaptain.com/mcp

Add this remote URL as a custom connector in Claude Desktop. Availability depends on the user plan and workspace policy.

Cursor

.cursor/mcp.json

{
  "mcpServers": {
    "x402-format-checker": {
      "url": "https://validate.crewofthecaptain.com/mcp"
    }
  }
}

Visual Studio Code

.vscode/mcp.json

Add to Visual Studio Code

{
  "servers": {
    "x402-format-checker": {
      "type": "http",
      "url": "https://validate.crewofthecaptain.com/mcp"
    }
  }
}

Generic MCP

Client-specific MCP configuration

{
  "name": "x402-format-checker",
  "transport": "streamable-http",
  "url": "https://validate.crewofthecaptain.com/mcp"
}

MCP Inspector

Run the official MCP Inspector locally and enter the indexed Streamable HTTP endpoint.

TRUST AND VERIFICATION EVIDENCE

Loading Trust v2 evidence…

Checking the associated registrable domain. The BuiltWith key remains server-side.

Indexed

Evidence is source-attributed and does not guarantee that a third-party server is safe. Risk labels are conservative metadata heuristics.