Crosswire — Polymarket & Kalshi Arbitrage

Cross-venue Polymarket+Kalshi arbitrage: resolution mismatch, void risk & settlement divergence.

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What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

    Cross-venue Polymarket+Kalshi arbitrage: resolution mismatch, void risk & settlement divergence.

    How to connect

    How to connect Crosswire — Polymarket & Kalshi Arbitrage to Claude

    The server address to paste into Claude settings:

    https://api.crosswire-api.com/mcp

    1. Open Claude (claude.ai or the desktop app).
    2. Go to Settings → Connectors.
    3. Click Add custom connector.
    4. Paste the server address copied below into Remote MCP server URL and click Add.
    5. In a chat, click + → Connectors and switch the new connector on.

    Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

    Authorization

    After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

    How to connect Crosswire — Polymarket & Kalshi Arbitrage to ChatGPT

    The server address to paste into ChatGPT settings:

    https://api.crosswire-api.com/mcp

    1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
    2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
    3. Open Settings → Connectors and click Create.
    4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
    5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
    6. In a new chat open + → Apps/Connectors and enable the connector.

    OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

    Authorization

    On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

    How to connect Crosswire — Polymarket & Kalshi Arbitrage to Cursor

    The server address to paste into Cursor settings:

    https://api.crosswire-api.com/mcp

    Fastest: click Open in Cursor below and confirm the prompt.

    Manually:

    1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
    2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
    3. Save the file. The server appears in the MCP list; authorize it there if asked.

    Authorization

    If the service needs sign-in, an authorize button appears next to the server in the MCP list.

    Server tool list (2)

    Raw names from tools/list. Only developers need these.

    check_resolution_riskPre-trade safety check for cross-venue event markets (crypto oracle-divergence pairs, metered; World Cup football, free). Flags resolution mismatches, void-rule divergence, scope differences (e.g. 90-minute vs extra-time; matched vs differing strike), settlement-source and -timing gaps, stale data, and thin liquidity between the two Polymarket and Kalshi legs BEFORE you execute both. Returns a machine-readable verdict — execution_verdict: safe / caution / block — inside a full Fungibility & Settlement Audit Object (FSAO) with structured findings, top-level divergence flags, venue rule overrides, fee-adjusted spread, and verdict reasons. Identify the pair by EITHER canonical_event_id (a live pair id from list_covered_events — the metered 'crypto:' inventory rolls daily, so fetch a current id there rather than reusing an old one; the free 'wc26:' World Cup pairs are stable) OR market_a + market_b (one Polymarket conditionId + one Kalshi ticker, order-insensitive). If the pair is not covered, returns a non-error coverage reply (covered: false) naming the covered inventories (free World Cup football + metered crypto pairs) and the coverage cutoff instead of an FSAO.
    list_covered_eventsFree discovery of everything check_resolution_risk can audit across both inventories — the free World Cup football pairs and the metered crypto oracle-divergence pairs (the 'crypto:' namespace is the paid surface: $0.02 USDC per call after 3 free calls/day). Returns the covered canonical events, their per-outcome pair ids (…#home / #draw / #away for football), the Polymarket conditionIds and Kalshi tickers with outcome labels for each pair, match dates, the frozen ruleset_sha pinning the identity graph, the coverage kickoff cutoff, and snapshot freshness. Use a returned pair_id (or a pair's two market ids) as input to check_resolution_risk.