/base-mcp

Hydrex Plugin

[!IMPORTANT] Run Base MCP onboarding first (see SKILL.md). Obtain the user's wallet address via get_wallets — it is required as from or recipient in every prepare call. The Hydrex prepare server must be running locally before any write operations.

Overview

Hydrex is an Omni-Liquidity MetaDEX on Base — concentrated-liquidity swaps aggregated across 0x, OpenOcean, OKX, and KyberSwap, plus liquidity positions that earn fees and rewards automatically. Adding liquidity creates an active earning position immediately; there is no separate staking step. The plugin calls a local prepare server (https://hydrex-agent.com) to fetch unsigned calldata, then submits via send_calls on Base mainnet (chainId: 8453).

Surface Routing

The prepare server (https://hydrex-agent.com) is not on the Base MCP web_request allowlist. On chat-only surfaces, construct the full GET URL with all query parameters and ask the user to open it in a browser, paste the JSON response into chat, then continue with send_calls.

Endpoints

Server URL: https://hydrex-agent.com

GET /health

Response: { "ok": true, "service": "hydrex-base-skill-server", "chainId": 8453 }

GET /state/quote

Response:

{
  "ok": true,
  "data": {
    "tokenIn": "0x...", "tokenOut": "0x...",
    "amountIn": "1000000", "amountOut": "412345678901234",
    "source": "ZEROX", "priceImpact": "0.12",
    "to": "0x...", "data": "0x...", "value": "0x0"
  }
}

Always show amountOut (human-readable) and priceImpact to the user before executing. Warn and require confirmation if priceImpact > 5%.

GET /state/portfolio

GET /state/portfolio?address=<walletAddress>

Returns token balances and LP positions for the wallet.

GET /state/positions

GET /state/positions?address=<walletAddress>

Returns all open concentrated liquidity positions owned by the wallet (read from NonfungiblePositionManager on-chain).

Response shape:

{
  "ok": true,
  "count": 2,
  "positions": [
    {
      "positionId": "12345",
      "token0": "0x...", "token1": "0x...",
      "fee": 500, "tickLower": -887220, "tickUpper": 887220,
      "liquidity": "1500000000000000",
      "tokensOwed0": "0", "tokensOwed1": "0"
    }
  ]
}

Use positionId with /prepare/remove-liquidity.

GET /state/trade-history

GET /state/trade-history?address=<walletAddress>

Returns past swaps executed through Hydrex for the wallet.

GET /state/pools

Discovers Hydrex pools — including each pool's contract address, token addresses, and decimals — from the Hydrex stats API. This is how the agent resolves a pool address (and token0/token1/decimals0/decimals1) for /prepare/add-liquidity and /prepare/remove-liquidity when the user only gives a token pair.

Pass tokenA + tokenB to find pools for a specific pair regardless of token order. With no token filters it returns every pool. Results are sorted by TVL (USD) descending, so pools[0] is the deepest pool for the pair.

Response:

{
  "ok": true,
  "count": 1,
  "summary": { },
  "pools": [
    {
      "id": "0x<poolAddress>",
      "pool": "0x<poolAddress>",
      "liquidityType": "integral",
      "fee": "500",
      "token0": { "address": "0x...", "symbol": "USDC", "name": "USD Coin", "decimals": 6 },
      "token1": { "address": "0x...", "symbol": "WETH", "name": "Wrapped Ether", "decimals": 18 },
      "tvlUsd": "1234567.89",
      "volumeUsd": "...", "feesUsd": "...", "averageFee": "..."
    }
  ]
}

Each entry gives the pool address plus token0/token1 addresses and decimals — exactly the inputs /prepare/add-liquidity needs (use them directly, preserving the returned token0/token1 order). Handling:

• count = 0 — no pool exists for that pair; tell the user and do not call a prepare endpoint.
• count > 1 — multiple pools/fee tiers; show the options (tvlUsd, fee, liquidityType) and let the user choose before proceeding.
• count = 1 — use it; confirm with the user before any write.

Never guess or fabricate a pool address — discover it here, or ask the user (addresses are also listed on the Hydrex app at https://hydrex.fi).

GET /prepare/swap

Example:

GET /prepare/swap?tokenIn=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&tokenOut=0x4200000000000000000000000000000000000006&amount=1.5&decimals=6&recipient=0xYourWallet&slippage=50

Response:

{
  "ok": true,
  "quote": {
    "tokenIn": "0x...", "tokenOut": "0x...",
    "amountIn": "1500000", "amountOut": "618522345678901",
    "source": "ZEROX", "priceImpact": "0.08"
  },
  "transactions": [
    { "step": "approve-tokenIn", "to": "0x<tokenIn>",   "data": "0x...", "value": "0x0", "chainId": 8453 },
    { "step": "swap",            "to": "0x<SwapRouter>", "data": "0x<calldata>", "value": "0x0", "chainId": 8453 }
  ]
}

The transactions[] array length is not fixed. For an ERC-20 tokenIn, an approve-tokenIn step is prepended only when the wallet's current allowance is too low — if allowance is already sufficient, just the swap step is returned. Native ETH swaps never include an approve step. Always pass every returned transaction to send_calls in order, rather than assuming a single call.

GET /prepare/add-liquidity

The range is set in exactly one of these mutually exclusive ways — rangePreset, a custom priceLower+priceUpper, or fullRange. Sending more than one returns 400 ("Choose only one range option…"); sending only one of priceLower/priceUpper returns 400 ("A custom range requires both…"). If you send none, the server uses the common preset (±12.5%).

Response — three transactions, always in this order:

{
  "ok": true,
  "position": { "tickLower": -887220, "tickUpper": 887220, "amount0": "0.05", "amount1": "100.0" },
  "transactions": [
    { "step": "approve-token0", "to": "0x<token0>", "data": "0x...", "value": "0x0", "chainId": 8453 },
    { "step": "approve-token1", "to": "0x<token1>", "data": "0x...", "value": "0x0", "chainId": 8453 },
    { "step": "mint",           "to": "0x<NFPM>",   "data": "0x...", "value": "0x0", "chainId": 8453 }
  ]
}

Price range selection

Choose one of three mutually exclusive ways to set the range (the server does the percentage→price math on-chain, so the agent only passes the choice):

If the user gives no preference, the server applies the common preset (±12.5%). Always tell the user which range was used, e.g. "I'm using the common ±12.5% range around the current price — say the word for a tighter (narrow/tight), wider (wide), full, or custom range."

GET /prepare/remove-liquidity

Response:

{
  "ok": true,
  "transactions": [
    { "step": "remove-liquidity", "to": "0x<NFPM>", "data": "0x...", "value": "0x0", "chainId": 8453 }
  ]
}

All prepare endpoints return { "ok": false, "error": "..." } on failure — surface the error field to the user and do not call send_calls.

Orchestration

Swap

1. get_wallets                                → address
2. GET /state/quote?tokenIn=...&tokenOut=...&amount=...&recipient=<address>
     → show amountOut (human-readable) and priceImpact
     → if priceImpact > 5%, warn user and require confirmation
3. GET /prepare/swap?tokenIn=...&tokenOut=...&amount=...&recipient=<address>
     → transactions[]
4. send_calls(chain="base", calls=[{to, value, data} for each tx])
5. get_request_status(requestId) — poll automatically until success or failed
     → report outcome; do NOT ask user to type anything

Add liquidity (enter a position)

1. get_wallets                                → address
2. GET /state/positions?address=<address>     → show existing positions for context
     → if count = 0 (no positions yet), that's fine — this will be the user's first
       position; continue without prompting for an existing one
3. Resolve the pool: GET /state/pools?tokenA=<t0>&tokenB=<t1>
     → count = 0: no pool exists, tell the user and stop
     → count > 1: show options (tvlUsd, fee, liquidityType) and let the user pick
     → use the chosen pool's pool/token0/token1/decimals; never guess an address
4. Confirm: pool address, token pair, amounts, range (preset/custom/full; default `common` ±12.5%)
5. GET /prepare/add-liquidity?from=<address>&pool=<pool>&token0=<t0>&token1=<t1>
       &decimals0=<d0>&decimals1=<d1>&amount0=<a0>&amount1=<a1>
       [ one range option only: &rangePreset=<tight|narrow|common|wide>
         | &priceLower=<p>&priceUpper=<p> | &fullRange=true ]
     → show position.tickLower, tickUpper, amount0, amount1 to user before proceeding
6. send_calls(chain="base", calls from transactions[])
7. get_request_status(requestId) — poll automatically until success or failed

Remove liquidity (exit a position)

1. get_wallets                                → address
2. GET /state/positions?address=<address>     → list positionId values
     → if count = 0 (no open positions), tell the user they have nothing to remove
       and stop — do not call /prepare/remove-liquidity
3. Confirm which positionId and what percentage to remove (default: 100%)
   → resolve the pool address with GET /state/pools?tokenA=<position.token0>&tokenB=<position.token1>
     (match on the position's fee tier when count > 1)
4. GET /prepare/remove-liquidity?from=<address>&positionId=<id>&pool=<pool>
       &decimals0=<d0>&decimals1=<d1>[&liquidityPercent=<pct>]
     → transactions[]
5. send_calls(chain="base", calls from transactions[])
6. get_request_status(requestId) — poll automatically until success or failed

Submission

Target tool: send_calls

Map every transactions[] array from a prepare endpoint into send_calls:

{
  "chain": "base",
  "calls": [
    { "to": "<tx.to>", "value": "<tx.value>", "data": "<tx.data>" }
  ]
}

Pass all transactions in a single calls array — Base MCP executes them atomically in one user approval. After send_calls returns, immediately call get_request_status(requestId) and poll until the status is success or failed. Do not ask the user to type or paste anything during polling. See approval-mode.md.

Example Prompts

"Swap 5 USDC for ETH on Hydrex"

1. get_wallets → wallet address
2. GET /state/quote?tokenIn=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&tokenOut=0x4200000000000000000000000000000000000006&amount=5000000&recipient=<address> → show amountOut, priceImpact
3. GET /prepare/swap?tokenIn=0x833589...&tokenOut=0x420000...&amount=5&decimals=6&recipient=<address>&slippage=50
4. send_calls(chain="base", calls=[swap tx])
5. Poll get_request_status → report outcome

"Show my Hydrex liquidity positions"

1. get_wallets → wallet address
2. GET /state/positions?address=<address> → display each positionId, token pair, tick range, and liquidity

"Add liquidity to the USDC/ETH pool on Hydrex — 100 USDC and 0.04 ETH"

1. get_wallets → wallet address
2. GET /state/positions?address=<address> → existing position context (count may be 0 — fine for a first position)
3. GET /state/pools?tokenA=USDC&tokenB=WETH → pick the pool (if count > 1, let the user choose); read its pool/token0/token1/decimals. Range defaults to the common preset (±12.5%) unless the user picks another; inform the user of the range used
4. GET /prepare/add-liquidity?from=<address>&pool=<pool>&token0=<USDC>&token1=<WETH>&decimals0=6&decimals1=18&amount0=100&amount1=0.04
5. Show returned position (tickLower, tickUpper, amounts) to user
6. send_calls(chain="base", calls=[approve-token0, approve-token1, mint])
7. Poll get_request_status → report outcome

"Remove 50% of liquidity from Hydrex position #12345" (chat-only surface fallback)

1. get_wallets → wallet address
2. web_request cannot reach https://hydrex-agent.com → construct the full URL and ask the user to open it in a browser and paste the JSON response into chat
3. On receiving JSON, send_calls(chain="base", calls from transactions[])
4. Poll get_request_status → report outcome

Risks & Warnings

• Slippage — swap and liquidity operations fill at market price; actual output can differ from the quote. Default tolerance is 50 bps (0.5%). Always check priceImpact before executing; if priceImpact > 5%, warn the user and wait for explicit confirmation. Never auto-raise slippage.
• Irreversible — onchain transactions cannot be undone once approved. Always show the user the full operation details (amounts, price range for LP positions, positionId for removals) and confirm before calling send_calls.

Notes

Well-known token addresses (Base mainnet)

For other tokens, look up the address (and decimals) via GET /state/pools (returns token0/token1 with address, symbol, and decimals), or ask the user to supply the contract address.

Error handling

Liquidity notes

• Adding liquidity creates a concentrated liquidity position that earns fees and rewards automatically — no separate staking step is required.
• Removing liquidity fully exits the position and returns both tokens to the wallet.
• The positionId is the NFT tokenId from the NonfungiblePositionManager; always fetch current positions via /state/positions before a remove.