oddsrail

The rail AI agents use to trade prediction markets.

An MCP server that gives any agent (Claude Code, Claude Desktop, or anything MCP-compatible) prediction-market access across Polymarket and Kalshi: market search, orderbooks, price history, positions, and order routing — with on-chain builder-code attribution on Polymarket — plus two premium signal tools (in-play overshoot/fade detection, resolution dispute-risk).

Free to use, and free of fees. oddsrail ships with a project builder code registered at 0 bps, so orders routed through it are attributed without adding a single basis point to anyone's trade. The project's income is a share of Polymarket's weekly builder reward pool — paid by Polymarket's own program, not by you. Running your own builder profile instead is one environment variable (ODDSRAIL_BUILDER_CODE), and server_info always tells you which code is in use. No fee tiers, no paywalled tools, no account required.

Why this and not Parsec

The closest competitor (parsecapi.com) is a closed-source hosted service: it stores your exchange keys (or holds a managed wallet that signs for you), and its Builder Program keeps 55–85% of the fees builders collect. oddsrail is the opposite on every axis: self-hosted, non-custodial (keys never leave your machine), open source, and you keep 100% of your Polymarket builder fees because attribution uses Polymarket's native mechanism, not a middleman escrow. Parsec also ships zero signal/analytics tools and nothing on resolution risk — that's our paid layer.

Quickstart

Python 3.11+ required.

pip install oddsrail

claude mcp add --transport stdio oddsrail -- oddsrail

Or from a clone, without installing:

python3 -m venv .venv && .venv/bin/pip install -r requirements.txt

claude mcp add --transport stdio oddsrail -- /abs/path/to/oddsrail/.venv/bin/python -m oddsrail.server

Then ask the agent: "search markets about the World Cup final and run the overshoot signal on the favorite".

How attribution works (CLOB V2, verified Aug 2026)

1. Get your builder code (a bytes32) at polymarket.com → Settings → Builders. Set your fee rates there: taker up to 100 bps, maker up to 50 bps — additive on top of platform fees, settled to your builder wallet.
2. export ODDSRAIL_BUILDER_CODE=0x... where the server runs.
3. Every order any agent routes through place_order has the code placed in the V2 order struct's builder field before signing — attribution is on-chain, visible in every OrderFilled event on CTF Exchange V2.
4. Verify with the builder_stats tool (public builder-trades endpoint + leaderboard).

If you skip this, orders carry the bundled oddsrail code at 0 bps — costing you nothing and funding the project. If you set your own, yours wins; the default is a default, not a lock-in.

Environment variables

Status — live-verified 2026-08-23

All 10 callable tools were driven end-to-end through a real MCP client session against live Polymarket, from the Finland VPS (/opt/oddsrail). Verified working: search, market lookup, orderbook (9/65 levels), price history (361 pts), overshoot signal, dispute-risk, builder leaderboard, dry-run order, open orders, server info.

Field mappings were corrected against the real API during that run — the docs-guessed shapes were wrong in three places (outcomes is a dict keyed yes/no, search() nests markets inside events, and book/volume/ resolution data live in prices/metrics/state/resolution sub-objects).

⚠️ Network note

Polymarket API domains are blocked on Turkish networks (BTK) — local testing fails TLS with a block page. Run the server where Polymarket is reachable (the Finland VPS at /opt/oddsrail, a VPN, or any unblocked network). The signal logic and MCP layer are fully testable offline.

Kalshi (venue #2)

Kalshi is bring-your-own-key and single-tenant by design: the operator supplies their own API key, trades their own account, and this server caches nothing. That is deliberate — Kalshi's Developer Agreement limits API use to a member's own trading (§3), bars facilitating other members' trading (§3.2) and sublicensing the API (§3.7), and restricts storing/sharing API data (§3.1). A hosted multi-tenant Kalshi service would not be compliant; a self-hosted one is.

Attribution does not exist here. Kalshi Builder Codes are a Solana/DFlow/Jupiter integration — there is no builder or affiliate field anywhere on the REST API, so Kalshi order flow cannot be attributed or monetised the way Polymarket's can. Kalshi is in oddsrail for coverage and signal reach, not for routing revenue.

Two shapes on this API are easy to get wrong, so oddsrail normalises both:

• Prices are dollar strings, not cents ("0.5600"), sizes are fixed-point strings ("10.00"); the legacy integer-cent fields were removed in March 2026. All arithmetic uses Decimal.
• The orderbook is bids-only on both sides. yes_dollars and no_dollars are both bid ladders, ascending — so the best bid is the last element, and a NO bid at $0.99 is a YES ask at $0.01. kalshi_get_orderbook returns a conventional best-first bid/ask view of the YES book plus the raw ladders.

Order placement speaks natural terms — outcome (yes/no), action (buy/sell), price = probability of that outcome — and translates to Kalshi's YES-book bid/ask internally (buy NO @ 0.25 becomes ask @ 0.75). That translation is unit-tested, since it is the obvious place to ship an inverted-position bug.

Credentials: KALSHI_KEY_ID plus KALSHI_PRIVATE_KEY_PATH (PKCS#8 PEM) or KALSHI_PRIVATE_KEY. Set KALSHI_DEMO=1 to hit the demo environment. Read tools need no key at all.

Tools (21)

• search_markets, get_market, get_orderbook, price_history, get_positions — read-only, no keys
• overshoot_signal — premium: fresh panic-jump detection + this market's historical reversion tendency (ported from the polymarket-wc analyzer)
• dispute_risk — premium: transparent 0–100 heuristic for contested (UMA-dispute-prone) resolutions
• place_order, cancel_order, open_orders — trading, dry-run by default
• builder_stats — attribution verification + public builder leaderboard
• server_info — config status, per-venue

Kalshi: kalshi_search_markets, kalshi_get_market, kalshi_get_orderbook, kalshi_get_trades, kalshi_balance, kalshi_positions, kalshi_open_orders, kalshi_place_order, kalshi_cancel_order.

Stack notes

• Official unified SDK polymarket-client (0.6.x): AsyncPublicClient for data, AsyncSecureClient.place_limit_order(..., builder_code=...) for attributed orders. The legacy py-clob-client is archived and cannot attach builder codes — do not use it.
• MCP SDK 2.0: MCPServer from mcp.server.mcpserver (the old mcp.server.fastmcp.FastMCP import is gone in 2.x).
• Kalshi is on plain httpx + cryptography, not the official SDK: kalshi-python-sync requires Python >=3.13 and re-releases weekly in lockstep with the spec version. Auth is RSA-PSS(SHA256, salt=digest length) over str(unix_ms) + METHOD + path, where the path includes /trade-api/v2 and excludes the query string. Base URL is now external-api.kalshi.com.
• x402 (planned): the official x402 PyPI package (v2.20+) can wrap MCP tools directly (x402.mcp, payment rides in tool-call _meta), but its MCP helpers currently target mcp 1.x — integrating means pinning mcp>=1.28,<2 or waiting for the 2.x-compatible release. Mainnet settlement needs a facilitator (Coinbase CDP: 1,000 free settlements/mo, then $0.001). Keep free tiers of both signals so registries can index the server.

What the builder economy looks like (live, 2026-08-23)

Pulled from the public leaderboard via builder_stats:

The instructive rows are the small-user ones: MagicMarkets routes $354K/week with 1 active user, Gate $1.11M/week with 2, PolymarketScan $277K with 3. Those are bot operators routing their own flow — oddsrail's exact target customer — and they show a single serious agent trader is worth real volume. Wallets (MetaMask, 37K users) dominate on user count, not on volume per user.

Roadmap

1. Live smoke test from an unblocked network — done 2026-08-23, all tools pass
2. Register builder code (polymarket.com → Settings → Builders), set fees to 0 bps at launch, export ODDSRAIL_BUILDER_CODE; first attributed order on a tiny size
3. Kalshi as venue #2 — done 2026-08-23, 9 tools, verified live
4. x402 paid wrapping for the two signals once the mcp-2.x conflict clears
5. Registry listings: official MCP registry (mcp-publisher, PyPI mcp-name: marker), Smithery (needs public streamable-HTTP + a free tool for their scanner), Glama (glama.json)

Listing / distribution

• GitHub: https://github.com/hmesutozsoy/oddsrail (public, MIT)
• Glama: auto-crawls GitHub; glama.json in the repo root claims maintainership.
• Official MCP registry: server.json is ready. Publishing needs the package on PyPI first (the registry verifies ownership via an mcp-name: io.github.hmesutozsoy/oddsrail marker in the PyPI README), then mcp-publisher login github && mcp-publisher publish.
• Smithery: requires a public HTTPS streamable-HTTP endpoint — available once oddsrail is hosted rather than run locally over stdio.