callx402 MCP server

Payload — Developer infrastructure for x402, agent payments, and programmable revenue.

PAYLOAD → VEYLINE (flagship) → CALLX402 (action layer) → REVRULE (separate) → developer products → free utilities.

This repo: callx402 by Payload — the universal action layer into Veyline's x402 infrastructure.

callx402 by Payload

Powered by Veyline. When x402 breaks, callx402.

callx402 is the universal action layer into Veyline's x402 infrastructure. Say what you need done in plain language (or hit an HTTP endpoint) and callx402 routes it to the production system that does the real work: diagnose a broken x402 payment, rescue a failed transaction, route an agent job to the cheapest viable path, resolve settlement state from on-chain evidence, or execute under an explicit budget with fail-closed safety rules.

Why it exists: x402 failures are expensive and opaque. A settlement attempt ends in settlement_pending and nobody knows whether the money moved. A 402 response your wallet misreads. A retry that signs a second authorization for the same intent and pays twice. callx402 exists for exactly those moments: diagnose pins the failure to a stage, rescue triages the incident, resolve settles the question from evidence, route finds the cheapest viable path, execute runs under a hard budget.

Try it (two minutes, no setup, no account):

npm install -g callx402
callx402 status
callx402 'complete this job for under $1'

status prints an honest per-subsystem reachability report, no credentials needed. The intent line parses and plans your request, then stops before executing anything: with no live tool endpoint wired it reports "no executable route available", so no money moves. (Use single quotes: in double quotes your shell would eat the $1.)

Free read-only checks against the live Payload rail:

curl https://payload-rail.fly.dev/v1/callx402/actions
curl 'https://payload-rail.fly.dev/v1/callx402/quote?action=diagnose'

The first returns the paid action catalog with prices; the second returns a free price quote for one action. Invoking a rail action is paid per action via checkout (see https://payloadhq.github.io/agents.json); these commands never pay anything.

If it saves you one debugging session, star the repo and read on.

MCP server: connect in 60 seconds

This repo ships a zero-dependency, read-only MCP server (mcp/index.js, node stdlib only, stdio transport) exposing six x402_* diagnostic tools. Nothing here charges, executes, retries, or repays.

git clone https://github.com/Payloadhq/callx402
# no npm install needed for the MCP server

Add this block to your MCP client config (replace the path), then restart the client:

{
  "mcpServers": {
    "callx402": {
      "command": "node",
      "args": ["/absolute/path/to/callx402/mcp/index.js"]
    }
  }
}

Ask the client to list its MCP tools: the six x402_* tools should appear. Per-client notes and the raw stdio test handshake: integrations/mcp-clients/.

Note: x402status works with zero setup. The other five tools dispatch into the v2.0.0 subsystem tree, so they report subsystemunreachable until CALLX402V2ROOT points at the tree (see "Full subsystem commands" above) and the matching flag is enabled.

The relationship

Shortened. The full README is on GitHub.