nsgoods workbench MCP

What it answers

A hosted Model Context Protocol server over our weekly full scan of the x402 catalogue: is this endpoint payable, what does it cost, which host is gone, which endpoints match a keyword, and whether a signed nsgoods response verifies offline.

Hosted endpoint: https://mcp.nsgoods.org/mcp (Streamable HTTP, no sign in, 300 tool calls per IP per day). Landing and docs: https://mcp.nsgoods.org/ · Health: https://mcp.nsgoods.org/health

Data is point in time from the last full scan. Every answer carries as_of and the scan id. For a live check of one endpoint before paying, use the paid /payable oracle on the hub. This server is the index.

Related MCP server: GPT55 x402 Gateway

Connect

Claude (web or desktop)

1. Settings, then Connectors, then Add custom connector

2. Name: nsgoods. URL: https://mcp.nsgoods.org/mcp. No sign in.

3. New conversation, then ask for example: Using nsgoods, find the cheapest payable endpoint for sanctions screening on Base

Cursor: add to mcp.json

{"mcpServers":{"nsgoods":{"url":"https://mcp.nsgoods.org/mcp"}}}

Smithery: https://smithery.ai/servers/nikosble1926/nsgoods-workbench

Any MCP client that supports Streamable HTTP works the same way.

Tools

All tools are read only and idempotent (declared through MCP tool annotations).

Verdicts: PAYABLE, NOT_PAYABLE, MALFORMED_402, CANNOT_PAY_EITHER_VERB, UNREACHABLE, SKIPPED, UNKNOWN.

Example

A live find_endpoints("erc20-balance", 2) call, trimmed to two rows:

{
  "query": "erc20-balance",
  "total_matches": 6,
  "returned": 2,
  "endpoints": [
    {
      "resource": "https://api.onesource.io/api/chain/erc20-balance",
      "host": "api.onesource.io",
      "last_verdict": "PAYABLE",
      "host_gone_since": null,
      "price": "0.003 USDC on eip155:8453"
    },
    {
      "resource": "https://app.heinrichstech.com/v1/cdp/chain/erc20-balance",
      "host": "app.heinrichstech.com",
      "last_verdict": "PAYABLE",
      "host_gone_since": null,
      "price": "0.003 USDC on eip155:8453"
    }
  ],
  "as_of": "2026-09-13",
  "index_scan_id": "scan-20260913T050332Z"
}

Data and freshness

Index is rebuilt after each weekly full scan (14,652 resources, 1,971 hosts, 13,146 payable as of 13 September 2026). Prices come from a sweep of the 402 challenges (10,958 endpoints priced, median 0.01 USDC, 16 September 2026). A per endpoint sample with a GET only re-probe outcome per row is published under CC BY 4.0: https://x402.nsgoods.org/proof/payability-sample-2026-09-13.json

Run your own

python -m venv venv && venv/bin/pip install -r requirements.txt

Put your own scans.jsonl (one JSON line per probe, see build_index.py for the fields) next to the scripts, then:

venv/bin/python build_index.py
venv/bin/python server.py   # listens on 127.0.0.1:4036, path /mcp

Docker:

docker build -t nsgoods-workbench-mcp . && docker run -p 4036:4036 nsgoods-workbench-mcp

Docker image is untested (built without a Docker host). Set WORKBENCH_HOST=0.0.0.0 inside containers. Feedback welcome.

Environment variables:

The server creates an empty index on first run if none is present, so tools/list works before you load any data.

Verification

Signed nsgoods responses use EIP-191 over canonical JSON (sorted keys, compact separators, ASCII escaped, signature and signed_by removed before hashing). The verify_signature tool checks the recovered address against the signers in https://x402.nsgoods.org/proof/index.json

Links

Landing https://mcp.nsgoods.org/ · Hub https://x402.nsgoods.org · MCP section https://x402.nsgoods.org/#mcp Weekly report https://x402.nsgoods.org/proof/payability-report-2026-09-13.html Methodology https://x402.nsgoods.org/ata-audit/payability_index.json (method field)

MIT license.