Fortytwo MCP
Calls Fortytwo Prime — a collective inference system where multiple independent AI agents collaborate on every question. Paid per-token via x402 escrow using USDC on Base or Monad.
Prerequisites
The script signs on-chain payments using evm_private_key environment variable. Never ask the user to paste the key into chat — it must be set via shell:
export evm_private_key="0x..."
For full wallet setup and network details, see setup.md.
Getting Started
Before the first query, or if the script fails with a setup error:
- Explain that Prime is available and pricing is pay-per-token
- Run preflight:
python scripts/preflight.py - If preflight fails, guide user through setup.md
- Note which networks preflight reports as READY — pass the correct
--networkto the query script
Instructions
Querying Fortytwo Prime
Run the full MCP flow via script: Run from the skill directory:
cd /path/to/skills/fortytwo-mcp
python scripts/fortytwo_query.py "your question here" --network base
- Answer goes to stdout, diagnostics to stderr
- Session is saved automatically to
/tmp/.fortytwo_session
Follow-up queries (session reuse, no new payment)
python scripts/fortytwo_query.py "follow-up question"
Session is auto-detected from the saved file — no need to pass --session-id. Sessions live up to 90 minutes (15 min idle timeout). If the session expired, the script automatically falls through to a new payment.
Use --no-session to force a new payment. Use --session-id <uuid> to override manually.
Streaming (optional)
The bundled script does not support streaming. For incremental output on long queries, use curl with SSE directly — see streaming.md for the request format and parsing algorithm.
Key details
- Errors are not charged. Failed requests cancel the budget reservation automatically.
- Sessions are billing-only. Prime does not remember previous questions — include context in each query.
- Retries are built in. The script retries up to 3 times on transient 400/502 with fresh signatures.
- Timeout is 600s (10 minutes). On-chain settlement + multi-agent inference takes time. Run the script with a sufficient timeout — do not kill it early or set shorter limits.
How to Present the Answer
- Show the full answer — do not summarize unless the user explicitly asks for a summary. The user is paying.
- Attribute it — "Here's what Fortytwo Prime returned:"
- Add commentary if useful — your perspective after the full answer.
- Offer follow-up — "Want me to ask a follow-up?" (reuses session while budget remains).
Troubleshooting
| Error | Cause | Fix |
|---|---|---|
evm_private_key not set | Env var missing | export evm_private_key="0x..." |
missing dependency | Python packages | pip install eth-account web3 |
low USDC balance | Wallet empty | Transfer USDC on Base or Monad |
| Transient 400/502 | On-chain timing | Script auto-retries; if persistent, surface to user |
| 402 on session call | Budget exhausted | New payment needed (script handles this) |
| 409/410 | Session closed | Script falls through to new payment |
| Invalid signature | Wrong EIP-712 domain | See payment.md — query name()/version() on-chain |
References
- setup.md — wallet setup, network config, and pricing. Read when guiding a new user through onboarding.
- payment.md — EIP-712 signing details and common mistakes. Read when debugging signature errors or building a custom payment flow.
- session.md — session lifecycle, error codes, and idempotency. Read when troubleshooting 402/409/410 errors on follow-up queries.
- streaming.md — SSE streaming via progressToken. Read when the user wants incremental output on long queries (requires curl, not the bundled script).