Arb Dex MCP Server

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

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 — get_chains, get_pairs and get_spreads answer, each carrying a limitation field naming exactly what the key would add. It never fabricates a row or silently degrades: get_prices, get_history_summary and get_history return an explicit key-required error with the signup link rather than a thinner answer dressed up as a full one.

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

Published on npm as arb-dex-mcp and listed in the official MCP Registry as io.github.donnywin85/arb-dex-mcp. Nothing to clone — your MCP client fetches it:

npx -y arb-dex-mcp

Requires Node 18+. That command starts the server on stdio, which is only useful to an MCP client; use one of the two configs below rather than running it by hand.

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": "npx",
      "args": ["-y", "arb-dex-mcp"],
      "env": {
        "RAPIDAPI_KEY": "your-rapidapi-key-here"
      }
    }
  }
}

Drop the env block entirely to run keyless — the server still starts and the free-snapshot tools still answer. 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 -- npx -y arb-dex-mcp

Or keyless:

claude mcp add arb-dex -- npx -y arb-dex-mcp

Then /mcp to confirm it connected.

Try it

Ask your agent. These work with no key, against the free hourly snapshot:

• "Which chains does arb-dex cover?"
• "Show me the cross-DEX spreads on Polygon — are any actually capturable?"

These need RAPIDAPI_KEY:

• "What is WBNB/USDT trading at on every BSC venue right now?"
• "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

Set these in your MCP client's env block (see the configs above). .env.example ships in the package and documents the same variables for local runs from a clone.

Test

The test suite is not in the npm tarball — run it from a clone:

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

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