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MCP server

rflow mcp serves the Model Context Protocol over stdio, so AI agents and editors (Claude Code, Cursor, anything that speaks MCP) can operate an rflow project: validate config, inspect the run journal and indexer cursors, simulate contract calls, and perform the same journaled, safe mutations the CLI exposes. An agent can debug a dead-lettered run, simulate the fix, and retry it without ever touching a key.

rflow mcp [--path <dir>]

Long-running; reads JSON-RPC from stdin, writes responses to stdout, logs to stderr. Exits cleanly when the client closes stdin. Reads rflow.yaml fresh on every call and connects to config.db_connection lazily, so config-only tools work before Postgres is up.

Claude Code / Cursor setup

Add rflow to your MCP config (.mcp.json for Claude Code, .cursor/mcp.json for Cursor):

{ "mcpServers": { "rflow": { "command": "rflow", "args": ["mcp", "--path", "/my/project"] } } }

Or one-shot with the Claude Code CLI:

claude mcp add rflow -- rflow mcp --path /my/project

The safety model

The tool surface is ops-level, not wallet-level:

  • Read-heavy by design — config, journal, cursors and health are read-only queries against rflow.yaml and the Postgres journal.
  • simulate_send never broadcasts — an eth_call through the same read providers the engine uses for pre-flight simulation. It never signs, never queues, never touches the relayer.
  • Mutations are the journaled safe ops only — trigger_workflow claims a manual run through the exactly-once gate (identical to rflow trigger), pause_workflow/resume_workflow flip the Postgres kill-switch, and retry_run requeues a settled run. Each lands in the durable journal and is executed by the running rflow start instance under the workflow's own permissions, simulation gates and relayer policies.
  • There is deliberately NO raw send/broadcast tool. Transactions only ever originate from workflow definitions; an agent cannot send an arbitrary transaction through rflow's relayers.
  • There is deliberately NO approve/reject tool either. An agent can see pending approval gates in the journal, but deciding a money gate stays with humans and the CLI.

Tools

ToolArgumentsWhat it does
validate_config—Strict collect-all validation of rflow.yaml; every error and warning.
get_config_summary—Networks (name, chain id), workflows (trigger, paused), relayers (networks, reconciled onchain address).
list_runslimit?, failed_only?Recent runs from the journal, newest first.
get_runrun_idOne run plus its full step journal: statuses, attempts, tx ids/hashes, outputs, errors.
list_triggerslimit?Trigger keys fired per workflow: which exact events/ticks claimed runs.
get_cursors—Indexer progress per workflow × network (anchor block, last processed block).
trigger_workflowworkflow, inputs?Claims a journaled manual run (manual:<uuid>), picked up by rflow start.
pause_workflowworkflowKill-switch: triggers keep matching, no new runs start.
resume_workflowworkflowResume a paused workflow.
retry_runrun_idRequeue a settled (failed | dead_letter | succeeded) run; resumes after its last completed step.
get_health—The /health payload: run counts per status, relayer count.
simulate_sendnetwork, contract_or_to, function?, args?, value?, data?, from?Read-only eth_call with decoded output, or the decoded revert reason.

Every result is compact JSON. Tool failures (unknown workflow, bad uuid, unreachable RPC) come back as in-band isError results with a precise message, so agents can read the reason and correct course.

simulate_send in practice

contract_or_to is either a name from your contracts: registry (the ABI and per-network address resolve automatically, function can be a bare name) or a raw 0x address (pass the full solidity signature, e.g. transfer(address,uint256)). value accepts 1 ether / 10 gwei / wei strings. A revert is a successful simulation with "success": false and the decoded reason, exactly what the engine's pre-flight simulation would have caught before a real send.

{ "network": "ethereum", "contract_or_to": "USDC", "function": "transfer", "args": ["0x…", "1000000"], "from": "0x…relayer" }

→

{ "success": false, "reverted": true, "reason": "execution reverted: ERC20: transfer amount exceeds balance" }