B3OS
MCP + x402

Onchain triggers,actions, and context.For your agent.

Make agent execution deterministic with one MCP server and composable onchain blocks that absorb RPC failures, reorgs, gas spikes, and stale indexes. Every run lands the same way, across every chain.

View docs
Works withClaude logoClaudeCodexCursorAny MCP client
1npm install -g @b3dotfun/b3os-mcp2 3b3os-mcp-setup4 5# restart Claude Desktop - done.

37 tools

loaded

HSM

signing

x402

ready

370
Action schemas
36
Chains supported
37
MCP tools
x402
Native support
01Quickstart

Your first workflow in minutes.

Install once, connect your agent, and start shipping. Most users go from package install to a published workflow in under a minute.

Install the MCP server

Install @b3dotfun/b3os-mcp globally and run b3os-mcp-setup. The wizard handles keychain storage and client config.

Connect your agent

Claude, Codex, Cursor, and other MCP clients can load workflow CRUD, run execution, action catalog, and wallet tools.

Build, query, and debug

Use natural language against persistent, observable, retryable workflows with full execution history.

Agent prompt
ready

Build a workflow that copytrades the top Polymarket trader by volume.

search_actions
create_workflow
publish_workflow

Example prompts

Ask your MCP client to assemble production workflows.

  • "Copytrade the top Polymarket trader by volume"

  • "Rebalance my Morpho yield into the highest APY vault"

  • "Trade the Twitter headline onchain the moment it drops"

  • "Pay contractors weekly in USDC from a Google Sheet"

  • "Sync paid invoices to QuickBooks automatically"

02Security

Sandboxed writes, HSM-backed keys, explicit approval.

Reads are frictionless. Writes are gated. Private keys never leave the HSM, and no middleman holds your API key.

b3os-mcp --sandbox

# Agent Environment:

DENIED - sandboxed

$ cat ~/.b3os/api_key

DENIED - keys vaulted in OS keychain

$ sign $TX_RAW

DENIED - requires explicit approval

$ rpc eth_sendRawTransaction

DENIED - rate-limited, retry queued

$ read balance(0xdeadbeef)

OK - allowed: reads are frictionless

Sandboxed execution

Every workflow run is isolated at the tenant boundary with scoped network access, no cross-tenant state bleed, and controlled egress.

Approval-gated writes

Reads can run freely. Workflow creation, publishing, and onchain execution require explicit approval per call.

Keys stay vaulted

Your B3OS API key stays in your OS keychain. Wallet signing happens server-side on Turnkey HSMs.

03Capabilities

Everything your agent can do.

The MCP server exposes the useful B3OS surface area without forcing agents to hand-roll blockchain execution.

Triggers

Schedules, webhooks, onchain events, token thresholds, Polymarket events, and social triggers start workflows when the world changes.

9 included
cronjob

Run on a cron schedule, from every minute to first of the month.

time
webhook

Trigger on inbound HTTP POST with optional x402 paywall support.

http
manual

Run on demand from the builder, CLI, API, or MCP b3os_run_workflow.

manual
evm-smart-contract-log

Fire on EVM logs matching a contract address and event signature.

onchain
evm-native-transfer

Fire when a wallet receives ETH, BNB, MATIC, or another native asset.

onchain
evm-erc20-received

Fire when a watched wallet receives an ERC-20 transfer.

onchain
token-price-threshold

Fire when a token crosses a configured price threshold.

market
polymarket-event

Fire on market moves, resolutions, and new listings.

market
slack-mention

Fire when your Slack app is mentioned in a channel.

social
04x402

Pay-per-request, no API key required.

B3OS speaks x402 in both directions, so agents with funded wallets can access services and execute workflows without separate onboarding.

Agent -> B3OS

Call any B3OS workflow

Hit a webhook URL. Get a 402 with USDC pricing on Base. Sign payment, resend, and B3OS executes the full automation.

  1. 1POST /webhook/:id
  2. 2402 with USDC price
  3. 3Sign payment and resend
  4. 4Workflow executes
B3OS -> Any x402 API

Call any x402-gated service

Discover endpoints, probe pricing, sign with the org Turnkey wallet, pay, and retry from a single workflow node.

  1. 1Discover endpoint
  2. 2Probe current price
  3. 3Turnkey HSM signs
  4. 4Response returns to node

Chain

Base primary

+ Ethereum, Optimism, Arbitrum, Polygon, BSC

Token

USDC and ERC-20

Facilitator auto-swaps when needed

Signing

Turnkey HSM

EIP-3009 and EIP-2612 permit

Price protection

5x cap

Auto-reject if price exceeds max

Give your agent B3OS tools.

Install the MCP package, connect your client, and use B3OS workflows as durable execution rails.

Open packageGitHub