arb-dex-mcp

An MCP server that gives an AI agent live cross-DEX market data on six EVM chains — BSC, Polygon, Arbitrum, Base, Avalanche and Optimism.

Every number is read from on-chain pool state at a stated block: per-venue pool price, pool TVL, and the gross cross-venue spread with the optimal trade size that captures it. Nothing is modelled, estimated or backfilled, and each payload carries its own scope note — so an agent that quotes a figure also has the caveats attached to it.

Backed by the Multi-Chain DEX Prices & Liquidity API.

Tools

| Tool | What it answers | Key needed | |---|---|---| | get_chains | Which chains are covered, their chain IDs, tokens and DEX venues | Optional — falls back to the free snapshot | | get_pairs | What is priceable on one chain: token universe, venues, pair syntax | Optional — falls back to the free snapshot | | get_prices | One pair's price at every venue holding a pool for it, plus reserves, TVL, fee tier and the cross-DEX spread | Required | | get_spreads | A whole chain's cross-venue dislocations, ranked by gross USD at the optimal size | Optional — free hourly snapshot without a key, fresh on-chain sweep with live: true | | get_history_summary | What the measurement archive covers: rows, pairs tracked, chains seen, span, retention | Required | | get_history | One pair's per-venue price/liquidity series and gross cross-venue spread over 24h / 7d / 30d | Required |

The two history tools read the service's own measurement archive, so they answer the question the live tools cannot: whether a dislocation persisted or was a single sample. Coverage is only what was measured — sampling is roughly hourly, and a gap stays a gap rather than being interpolated or backfilled. Call get_history_summary first to see what span exists before asking for a window.

Without a key the server still runs and returns real data from the free public surface, labelled as such. It never fabricates a row or silently degrades: a paid call with no key returns an explicit key-required error with the signup link.

Spreads are gross — before gas, MEV and slippage beyond the optimal size. Not a profit estimate and not trade advice. A wide spread against a shallow pool is worth very little, and get_spreads says so per row rather than letting a big basis-point number mislead.

Install

git clone https://github.com/donnywin85/arb-dex-mcp.git
cd arb-dex-mcp
npm install

Requires Node 18+.

Get a key

The paid tools call the API through RapidAPI using your own key. This package ships no credentials of any kind.

1. Subscribe (there is a free tier): https://rapidapi.com/donnydev/api/multi-chain-dex-prices-liquidity
2. Copy your X-RapidAPI-Key from the RapidAPI dashboard.
3. Put it in RAPIDAPI_KEY in the config below — never in code, and never in a commit.

Claude Desktop

claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\):

{
  "mcpServers": {
    "arb-dex": {
      "command": "node",
      "args": ["/absolute/path/to/arb-dex-mcp/src/index.mjs"],
      "env": {
        "RAPIDAPI_KEY": "your-rapidapi-key-here"
      }
    }
  }
}

Restart Claude Desktop; the six tools appear under the connectors icon.

Claude Code

claude mcp add arb-dex --env RAPIDAPI_KEY=your-rapidapi-key-here -- node /absolute/path/to/arb-dex-mcp/src/index.mjs

Then /mcp to confirm it connected.

Try it

Ask your agent:

• "Which chains and DEX venues does arb-dex cover?"
• "What is WBNB/USDT trading at on every BSC venue right now?"
• "Show me the cross-DEX spreads on Polygon — are any actually capturable?"
• "Run a live spread sweep on Arbitrum and rank by gross USD."
• "How much history does arb-dex actually have, and for which chains?"
• "Did the WETH/USDC spread on Base persist over the last 24h or was it one sample?"

Configuration

| Env var | Default | Purpose | |---|---|---| | RAPIDAPI_KEY | — | Your RapidAPI key. Required for paid tools. | | ARB_DEX_TIMEOUT_MS | 45000 | Request timeout. A live full-chain sweep is a real on-chain read and can take ~30s. | | ARB_DEX_FREE_BASE_URL | production origin | Override the free-surface host. | | ARB_DEX_RAPIDAPI_HOST | multi-chain-dex-prices-liquidity.p.rapidapi.com | Override the RapidAPI host. |

See .env.example.

Test

npm run selftest                    # keyless: exercises the free fallbacks
RAPIDAPI_KEY=... npm run selftest   # keyed: exercises the paid routes

The test spawns the server over stdio and calls every tool against the real production API — nothing is mocked. It asserts on live values (block number, per-venue prices, scanned-pair counts), so a run that passes is evidence the data path works end to end.

Closed gap

The API's paid measurement archive (/v1/history/*) was live on the origin but unlisted on RapidAPI, so calls through the proxy 404'd and get_history was deliberately held back rather than shipped broken. Both routes were published on the listing on 2026-08-11 and re-measured through the proxy the same day — summary 200, pair series 200, unsupported window 400 — so get_history_summary and get_history ship as tools, each covered by a live keyed assertion in the selftest.

License

MIT