Cross-DEX Prices & Spreads

arb-dex-mcp

Live cross-DEX crypto prices for your AI agent — per-venue pool price, pool liquidity and the gross cross-venue spread on 6 EVM chains, read straight from on-chain pool state.

Chains: BSC · Polygon · Arbitrum · Base · Avalanche · Optimism. Venues: PancakeSwap (v2 + v3), Uniswap v3, SushiSwap, QuickSwap, Biswap, ApeSwap, BaseSwap, Trader Joe, Pangolin — every v2-style pool and every v3 fee tier separately, because a $12k 1% pool and a $19M 0.01% pool are not the same quote.

Nothing is modelled, estimated or backfilled. Every payload states its own block number and carries its own scope note, so an agent that quotes a figure also has the caveats attached to it.

Works with no API key against a free hourly public snapshot. Docs · npm

Quickstart

Nothing to clone or build. Your MCP client fetches the package. Requires Node 18+.

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" } } } }

Restart Claude Desktop; the six tools appear under the connectors icon. Drop the `env` block entirely to run keyless — the server still starts and the free-snapshot tools still answer.

Claude Code

claude mcp add arb-dex --env RAPIDAPI_KEY=your-rapidapi-key-here -- npx -y arb-dex-mcp

Keyless:

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

Then /mcp to confirm it connected.

Cursor

~/.cursor/mcp.json (global) or .cursor/mcp.json (per project):

{

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

Cursor → Settings → MCP shows the server and its tools once the file is saved.

Any other MCP client

Same three facts: command npx, args ["-y", "arb-dex-mcp"], transport stdio, optional env RAPIDAPI_KEY.

Try it

Real prompts, and the real shape that comes back. Payloads below were measured live on 2026-08-15; they are trimmed for width but nothing is invented.

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

get_prices reads every pool holding the pair — v2 pairs and each v3 fee tier separately — at one stated block:

{

"pair": "WBNB/USDT", "network": "bsc", "chainId": 56, "blockNumber": 116151268, "pricesByVenue": [ { "venue": "pancake", "surface": "v2", "feeBps": 25, "price": 611.7347, "tvlUsd": 56834814.36 }, { "venue": "biswap", "surface": "v2", "feeBps": 10, "price": 610.8278, "tvlUsd": 415733.94 }, { "venue": "apeswap", "surface": "v2", "feeBps": 20, "price": 611.1244, "tvlUsd": 3659.06 }, { "venue": "pancakeV3:1", "surface": "v3", "feeBps": 1, "price": 610.5684, "tvlUsd": 18596810.32 }, { "venue": "pancakeV3:5", "surface": "v3", "feeBps": 5, "price": 610.6531, "tvlUsd": 4941099.44 }, { "venue": "pancakeV3:25", "surface": "v3", "feeBps": 25, "price": 610.6304, "tvlUsd": 52534.35 }, { "venue": "pancakeV3:100", "surface": "v3", "feeBps": 100, "price": 609.1025, "tvlUsd": 12206.21 } ], "bestBuy": { "venue": "pancakeV3:100", "price": 609.1025 }, "bestSell": { "venue": "pancake", "price": 611.7347 }, "midSpreadBps": 43.22, "crossDex": { "grossSpreadBps": 0, "grossUsd": 0, "optimalInput": { "amount": 0, "token": "WBNB", "usd": 0 }, "buyVenue": "-", "sellVenue": "-" }, "liquidity": { "venues": 7, "totalTvlUsd": 80856857.67 }, "source": "rpc" }

Read the two spread numbers against each other. The raw mid spread is 43 bps — and the gross capturable spread is 0. The 609.10 quote lives in a $12k pool; the size that would actually clear it moves the price past the gap before you get there. A tool that reported only the 43 bps would be handing an agent a number it cannot trade. This one reports both, and optimalInput is where the honesty lands.

2. "Show me the cross-DEX spreads on Base — are any actually capturable?"

get_spreads sweeps a whole chain and ranks by gross USD at the optimal size, not by headline basis points:

{

"network": "base", "chainId": 8453, "scannedPairs": 11, "opportunities": [], "found": 0, "filters": { "minSpreadBps": 10, "minVenueTvlUsd": 1000, "minGrossUsd": 0.01, "limit": 5 }, "ranking": "gross USD at the optimal trade size, NOT raw spread — a large spread with a tiny optimal size is not an opportunity", "scope": "GROSS cross-venue spread from live pool state, BEFORE gas, MEV and any slippage beyond the optimal size. Not a profit estimate and not trade advice. Venues below the liquidity floor are excluded because a spread against a dust pool is an artefact, not an opportunity.", "elapsedMs": 2847 }

`found: 0` is a real answer and it is the common one. Eleven pairs scanned, nothing cleared the floor. Venues under $1,000 TVL are dropped outright. When rows *do* come back, each carries capturable, warning and shallowestSideTvlUsd so a big basis-point number cannot mislead on its own. This tool will tell your agent there is nothing there — which is the whole point of asking it.

3. "How much history does arb-dex actually have, and for which chains?"

get_history_summary sizes the archive *before* you query it:

{

"rows": 133, "rowsWithPairDetail": 103, "rowsByEra": { "digest-totals-only": 30, "top-list-pairs": 5, "full-sweep": 98 }, "pairsTracked": 107, "firstAt": "2026-08-10T17:35:09.355Z", "lastAt": "2026-08-15T20:54:34.417Z", "spanHours": 123.32, "chainsSeen": ["arbitrum", "avalanche", "base", "bsc", "optimism", "polygon"], "pairs": [ { "chain": "polygon", "pair": "WBTC/USDC", "observations": 103, "qualifiedObservations": 39 }, { "chain": "bsc", "pair": "BTCB/USDT", "observations": 99, "qualifiedObservations": 15 }, { "chain": "arbitrum", "pair": "ARB/USDC", "observations": 98, "qualifiedObservations": 0 } ] }

Coverage is only what was measured. A gap stays a gap — rowsByEra says how much detail each era of rows carries, and ARB/USDC having 98 observations but 0 qualified is the archive telling you that pair has never once cleared the spread floor.

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. Sampling is roughly hourly, and gaps are never interpolated or backfilled. Call get_history_summary first to see what span exists before asking for a window.

What it will not do

• Spreads are gross — before gas, MEV and slippage beyond the optimal size. Not a profit estimate and not trade advice.
• It never fabricates a row. Without a key, get_chains, get_pairs and get_spreads answer from the free public surface and each carries a limitation field naming exactly what a key would add. 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.
• It does not execute trades, hold funds, or touch a wallet. It is read-only market data.
• This package ships no credentials of any kind. The key is yours and stays in your config.

Get a key

The paid tools call the API through RapidAPI using your own key.

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 above — never in code, and never in a commit.

Plans

Five of the six tools work on the free tier. Only the per-pair history series is gated:

Calling get_history below PRO returns an explicit tier_required error naming the plan and the upgrade URL — it does not fail silently or return an empty series.

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.

Links

• npm: https://www.npmjs.com/package/arb-dex-mcp
• Docs: https://donnywin85.github.io/arb-dex-mcp/
• Official MCP Registry: io.github.donnywin85/arb-dex-mcp
• TensorBlock MCP Index: https://www.tensorblock.co/mcp/servers/github-donnywin85-arb-dex-mcp-7dd9a70c
• Sour