MCP.Market

Crosswire — Polymarket & Kalshi Arbitrage MCP server

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by crosswire-api.com·com.crosswire-api/crosswire-polymarket-kalshi-arbitrage·v0.6.2·1 stars
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Cross-venue Polymarket+Kalshi arbitrage: resolution mismatch, void risk & settlement divergence.

B80/100grade B
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B80/100

full report

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Crosswire — Polymarket & Kalshi Arbitrage tools (2)

write = sends, deletes, buys or posts
  • check_resolution_riskFree

    Pre-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

    Free 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.

Public scan report

scanner v0.1.9 · 2026-09-26 · same rubric, same numbers if you re-run it

no findings
  • –Code scanremote-only server, no package to scann/a
  • Live reliabilityremote reachable in 623ms20/20
  • Tool poisoning2 tool descriptions checked15/15
  • Auth qualityopen endpoint, read-only tools10/15
  • Maintenancelast push 97 days ago8/15
  • Maintainer identitynamespace and repository owner differ; GitHub account older than a year; website matches verified namespace7/10
Overall 80/100. Components that don't apply are left out of the denominator. Any critical finding is an F.RubricAppeal a findingJSON

How Crosswire — Polymarket & Kalshi Arbitrage compares

Against every graded MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score
80/100
higher than 60% of 48,255 servers
Tools
2
the typical server has 7
Tools that change things
0%
typical: 0%. Fewer write tools means less an agent can break
Uptime
100%
of our recent checks; the typical remote server answers 100%
Response time
217 ms
faster than 61% of 30,031 servers
GitHub stars
1
more than 65% of 28,688 servers

What its tools let an agent do: 2 read

Install Crosswire — Polymarket & Kalshi Arbitrage in Claude Code, Cursor or VS Code

claude mcp add --transport http crosswire-polymarket-kalshi-arbitrage https://api.crosswire-api.com/mcp
Add to Cursor

What the publisher says

From the Crosswire — Polymarket & Kalshi Arbitrage repository's README, as published. We do not edit it. Read it on GitHub

Crosswire — MCP server

Pre-trade resolution-risk firewall for cross-venue prediction-market arbitrage. Before executing a two-leg Polymarket + Kalshi position, Crosswire flags resolution mismatch, void risk, and settlement divergence — void-rule asymmetry, settlement-scope differences (90-minute vs extra-time), settlement-source and -timing gaps, stale data, and thin liquidity between Polymarket and Kalshi FIFA World Cup 2026 markets — so automated trading agents don't get blown up by markets that look identical but settle differently. Verdict: safe / caution / block.

It does not predict outcomes and it does not execute trades. It answers one question: if I buy this contract on one venue and sell its twin on the other, do they actually settle on the same thing? When they don't, it names the exact clause that breaks the hedge.

Remote MCP endpoint

https://api.crosswire-api.com/mcp
  • Transport: streamable HTTP
  • The MCP tools are free — no API key, no signup
  • Website: crosswire-api.com · Status & track record: api.crosswire-api.com

Connect

Generic MCP client config (mcp.json):

{
  "mcpServers": {
    "crosswire": {
      "url": "https://api.crosswire-api.com/mcp"
    }
  }
}

Claude Code:

claude mcp add --transport http crosswire https://api.crosswire-api.com/mcp

Tools

checkresolutionrisk

Pre-trade safety check for a cross-venue pair. 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:

e.g. "wc26:match:MEX-RSA:2026-06-11:result#home" (#home / #draw / #away selects the outcome leg), or

  1. canonicaleventid — a pair id from listcoveredevents,

(e.g. KXWCGAME-26JUN11MEXRSA-MEX), order-insensitive. outcome on a ref is optional — matching uses only (venue, market_id).

  1. marketa + marketb — one Polymarket conditionId (0x… hex) and one Kalshi ticker

Optional: notional_usd (enables the thin-liquidity check at your trade size).

If the pair is not covered, the tool returns a non-error coverage reply (covered: false) naming the covered matches and the coverage cutoff instead of an FSAO.

Example — real production audit (World Cup opener, Mexico vs South Africa, home leg):

Request:

{
  "canonical_event_id": "wc26:match:MEX-RSA:2026-06-11:result#home"
}

Response (abridged with …):

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Crosswire — Polymarket & Kalshi Arbitrage: common questions

Is Crosswire — Polymarket & Kalshi Arbitrage MCP server safe?
Mostly: it is graded B (80/100). Read the Crosswire — Polymarket & Kalshi Arbitrage safety report
How do I install Crosswire — Polymarket & Kalshi Arbitrage?
It runs remotely at api.crosswire-api.com. Add it to Claude Code, Cursor, VS Code or Claude Desktop with the snippets above, or call it through the mcp.market gateway without installing anything.
Does Crosswire — Polymarket & Kalshi Arbitrage need an API key?
Not as far as the registry entry and our scan can tell: no credentials are declared or required.
Is Crosswire — Polymarket & Kalshi Arbitrage maintained?
The last commit was 136 days ago (2026-06-21). The latest release is v0.6.2.
Is Crosswire — Polymarket & Kalshi Arbitrage up?
100% of our last 28 checks got an answer. We check remote servers about four times a day.
How does Crosswire — Polymarket & Kalshi Arbitrage compare with other MCP servers?
safety score 80/100 (higher than 60% of 48,255 servers); tools 2 (the typical server has 7); tools that change things 0% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.