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

Capability	Harness surface (Cursor, Claude Code, Codex)	Chat-only surface (Claude.ai, ChatGPT)
Read state (quote, positions, portfolio, pools)	Harness HTTP tool → `GET https://hydrex-agent.com/state/*`	User-paste fallback: construct full URL, ask user to open in browser and paste JSON response
Prepare calldata (swap, add/remove liquidity)	Harness HTTP tool → `GET https://hydrex-agent.com/prepare/*`	User-paste fallback: same as above
Submit transaction	`send_calls` (Base MCP)	`send_calls` (Base MCP)

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

Parameter	Type	Required	Description
`tokenIn`	address	✓	Input token contract address
`tokenOut`	address	✓	Output token contract address
`amount`	string (wei)	✓	Input amount in raw units
`recipient`	address	✓	Wallet that receives output tokens
`slippage`	number	—	Slippage tolerance in bps (default: 50 = 0.5%)
`source`	string	—	Force aggregator: `ZEROX`, `OPENOCEAN`, `OKX`, `KYBERSWAP`

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.

Parameter	Type	Required	Description
`tokenA`	string	—	Token symbol (e.g. `USDC`) or address; matches either side of the pair (order-independent)
`tokenB`	string	—	Second token symbol or address, for unordered pair matching
`token0`	string	—	Order-specific token0 symbol or address
`token1`	string	—	Order-specific token1 symbol or address
`liquidityType`	string	—	Filter by pool type: `integral`, `classic-volatile`, `classic-stable`
`days`	number	—	Stats lookback window in days, 1–30 (default: 1)
`limit`	number	—	Max upstream pairs to scan, 1–1000 (default: 1000)

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

Parameter	Type	Required	Description
`tokenIn`	address	✓	Input token address
`tokenOut`	address	✓	Output token address
`amount`	string	✓	Human-readable input amount (e.g. `"1.5"`)
`decimals`	number	—	Decimals of `tokenIn` (default: 18)
`recipient`	address	✓	Wallet that receives output tokens
`slippage`	number	—	Slippage in bps (default: 50)
`source`	string	—	Optional aggregator override

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

Parameter	Type	Required	Description
`from`	address	✓	Wallet providing liquidity
`pool`	address	✓	Pool contract address — resolve from the token pair via `GET /state/pools`, or ask the user (also listed on https://hydrex.fi)
`token0`	address	✓	token0 address (must match pool order)
`token1`	address	✓	token1 address (must match pool order)
`decimals0`	number	—	token0 decimals (default: 18)
`decimals1`	number	—	token1 decimals (default: 18)
`amount0`	string	✓	Desired token0 amount, human-readable
`amount1`	string	✓	Desired token1 amount, human-readable
`rangePreset`	string	—	Named range around current price: `tight` (±1%), `narrow` (±5%), `common` (±12.5%), `wide` (±20%). Used when no other range option is given (default: `common`)
`priceLower`	number	—	Custom lower price bound (token1/token0). Must be sent together with `priceUpper`
`priceUpper`	number	—	Custom upper price bound (token1/token0). Must be sent together with `priceLower`
`fullRange`	boolean	—	If `true`, spreads liquidity across the entire price range (always-active, V2-style). Default `false`
`slippage`	number	—	Slippage in bps (default: 50)

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):

Option	How to send it	Resulting range
Named preset	`rangePreset=tight`	±1% of current price
Named preset	`rangePreset=narrow`	±5%
Named preset	`rangePreset=common` (default)	±12.5%
Named preset	`rangePreset=wide`	±20%
Custom	`priceLower=<p>&priceUpper=<p>`	exact bounds you supply
Full range	`fullRange=true`	entire price range (always-active)

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

Parameter	Type	Required	Description
`from`	address	✓	Wallet that owns the position
`positionId`	number	✓	NFT tokenId from `/state/positions`
`pool`	address	✓	Pool contract address — the matching position from `/state/positions` identifies the pair (`token0`/`token1`/`fee`); resolve the address via `GET /state/pools` (or ask the user)
`decimals0`	number	—	token0 decimals (default: 18)
`decimals1`	number	—	token1 decimals (default: 18)
`liquidityPercent`	number	—	Percentage to remove, 1–100 (default: 100)
`slippage`	number	—	Slippage in bps (default: 50)

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”

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

“Show my Hydrex liquidity positions”

get_wallets → wallet address
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”

get_wallets → wallet address
GET /state/positions?address=<address> → existing position context (count may be 0 — fine for a first position)
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
GET /prepare/add-liquidity?from=<address>&pool=<pool>&token0=<USDC>&token1=<WETH>&decimals0=6&decimals1=18&amount0=100&amount1=0.04
Show returned position (tickLower, tickUpper, amounts) to user
send_calls(chain="base", calls=[approve-token0, approve-token1, mint])
Poll get_request_status → report outcome

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

get_wallets → wallet address
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
On receiving JSON, send_calls(chain="base", calls from transactions[])
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)

Symbol	Address	Decimals
USDC	`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`	6
WETH	`0x4200000000000000000000000000000000000006`	18
ETH (native)	Use the `value` field; no `tokenIn` address needed	18

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

Condition	Action
`get_wallets` returns no wallet	Tell user to connect their Base Account and retry
`/state/positions` returns `count: 0`	For add-liquidity, proceed — this is the user’s first position. For remove-liquidity, tell the user they have no open positions and stop
Pool address unknown	Resolve via `GET /state/pools` (by token pair); if it returns `count: 0`, no pool exists — tell the user and stop. Never guess an address
`/state/pools` returns `count > 1`	Multiple pools/fee tiers for the pair; show `tvlUsd`/`fee`/`liquidityType` and let the user choose
`/state/quote` returns `priceImpact > 5%`	Warn user; require confirmation before proceeding
Prepare endpoint returns `ok: false`	Surface the `error` field; do not call `send_calls`
`send_calls` approval rejected	Inform user the transaction was cancelled; offer to retry
`get_request_status` shows failure	Parse the failure reason and suggest next steps

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.

​Hydrex Plugin

​Overview

​Surface Routing

​Endpoints

​GET /health

​GET /state/quote

​GET /state/portfolio

​GET /state/positions

​GET /state/trade-history

​GET /state/pools

​GET /prepare/swap

​GET /prepare/add-liquidity

​Price range selection

​GET /prepare/remove-liquidity

​Orchestration

​Swap

​Add liquidity (enter a position)

​Remove liquidity (exit a position)

​Submission

​Example Prompts

​Risks & Warnings

​Notes

​Well-known token addresses (Base mainnet)

​Error handling

​Liquidity notes

Hydrex Plugin

Overview

Surface Routing

Endpoints

GET /health

GET /state/quote

GET /state/portfolio

GET /state/positions

GET /state/trade-history

GET /state/pools

GET /prepare/swap

GET /prepare/add-liquidity

Price range selection

GET /prepare/remove-liquidity

Orchestration

Swap

Add liquidity (enter a position)

Remove liquidity (exit a position)

Submission

Example Prompts

Risks & Warnings

Notes

Well-known token addresses (Base mainnet)

Error handling

Liquidity notes