/base-mcp

Uniswap Plugin

[!IMPORTANT] Complete the short Base MCP onboarding flow defined in SKILL.md before calling any Uniswap endpoint. The user's wallet address — passed as walletAddress in every swap and LP call — is fetched lazily when needed.

Overview

Uniswap on Base: token swaps using the proxy-approval flow (no Permit2 signing) and LP position management for V2, V3, and V4. The plugin fetches unsigned calldata from the Uniswap API, then executes transaction previews with send_calls. No additional MCP server is required.

Chain: Base mainnet (chainId 8453).

Auth

Use these headers for all requests:

{
  "Content-Type": "application/json",
  "x-api-key": "NeoYO3V50_koJAipDEalYWbMO1XMaFPAQmpOm6_Npo0"
}

For the swap proxy-approval flow, also include this header on all swap endpoints: /check_approval, /quote, and /swap.

{
  "x-permit2-disabled": "true"
}

Without x-permit2-disabled, Uniswap can return Permit2 or Universal Router behavior instead of the proxy-approval flow described here.

Surface Routing

Uniswap is HTTP-only; every capability follows the standard HTTP routing in ../references/custom-plugins.md.

Prerequisite: trade-api.gateway.uniswap.org and liquidity.api.uniswap.org must be in the MCP server's web_request allowlist. If requests are rejected by the allowlist and no harness HTTP tool is available, inform the user.

Endpoints

Swap endpoints: proxy approval, no Permit2

Base URL: https://trade-api.gateway.uniswap.org/v1

POST /check_approval  ->  if approval non-null, include approval calldata in send_calls
POST /quote           ->  get best route, read-only
POST /swap            ->  get unsigned swap tx, include swap calldata in send_calls

1. POST /check_approval

Headers: auth headers plus "x-permit2-disabled": "true".

{
  "walletAddress": "<address>",
  "token": "<tokenIn address>",
  "amount": "<base units string>",
  "chainId": 8453,
  "includeGasInfo": true
}

Response:

{
  "approval": {
    "to": "<token contract>",
    "data": "<calldata>",
    "value": "0x00",
    "chainId": 8453
  }
}

approval can be null, especially for native ETH. If it is non-null, pass it to send_calls. You can batch the approval and swap together after /swap returns.

2. POST /quote

Headers: auth headers plus "x-permit2-disabled": "true".

{
  "type": "EXACT_INPUT",
  "amount": "<base units string>",
  "tokenIn": "<address or 0x0000000000000000000000000000000000000000 for native ETH>",
  "tokenOut": "<address>",
  "tokenInChainId": 8453,
  "tokenOutChainId": 8453,
  "swapper": "<address>",
  "autoSlippage": "DEFAULT",
  "protocols": ["V4", "V3", "V2"],
  "routingPreference": "BEST_PRICE"
}

Use "slippageTolerance": <0-20> instead of autoSlippage if the user specifies slippage. See Risks & Warnings before submitting elevated values.

Response includes a top-level quote object plus metadata. Keep the response as a flat object for /swap; do not nest it under a quote key.

3. POST /swap

Headers: auth headers plus "x-permit2-disabled": "true".

Use the /quote response as the body, but remove any null or absent permit fields before sending:

const swapBody = { ...quoteResponse };
if (swapBody.permitData == null) delete swapBody.permitData;
if (swapBody.permitTransaction == null) delete swapBody.permitTransaction;
delete swapBody.signature;

Do not send signature, and do not send permitData or permitTransaction when they are null.

Response:

{
  "swap": {
    "to": "<router or proxy>",
    "data": "<calldata>",
    "value": "0x00",
    "chainId": 8453
  },
  "gasFee": "..."
}

LP endpoints

Base URL: https://liquidity.api.uniswap.org/lp

Use this host for LP endpoints in this plugin environment. Do not switch to api.uniswap.org or trade-api.gateway.uniswap.org/v1/lp/... unless that host is explicitly available to the API key and MCP allowlist.

Pool Discovery: POST /lp/pool_info

Use pool discovery before creating V3/V4 LP positions. poolReference must be a valid pool address for V3 or pool ID for V4.

{
  "protocol": "V4",
  "chainId": 8453,
  "poolParameters": {
    "tokenAddressA": "0x0000000000000000000000000000000000000000",
    "tokenAddressB": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "fee": 3000,
    "tickSpacing": 60
  }
}

Known Base V4 ETH/USDC fee=3000, tickSpacing=60 pool reference observed in testing:

0xe070797535b13431808f8fc81fdbe7b41362960ed0b55bc2b6117c49c51b7eb9

Pool references can change by pair, fee, tick spacing, and protocol. Prefer querying /lp/pool_info instead of hard-coding a pool reference unless the user explicitly selected a pool.

Approval Step: POST /lp/check_approval

Use this before LP create/increase/decrease operations. The body uses lpTokens as an array of token/amount objects.

{
  "protocol": "V4",
  "walletAddress": "<address>",
  "chainId": 8453,
  "lpTokens": [
    {
      "tokenAddress": "0x0000000000000000000000000000000000000000",
      "amount": "<base units>"
    },
    {
      "tokenAddress": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "amount": "<base units>"
    }
  ],
  "action": "CREATE",
  "generatePermitAsTransaction": true,
  "simulateTransaction": true
}

action: "CREATE" | "INCREASE" | "DECREASE" | "MIGRATE"

Response:

{
  "requestId": "...",
  "transactions": [
    {
      "transaction": {
        "to": "...",
        "from": "...",
        "data": "...",
        "value": "0x00",
        "chainId": 8453
      },
      "cancelApproval": false,
      "action": "CREATE"
    }
  ]
}

If transactions is empty, no approval transaction is needed. If it has entries, map every transactions[*].transaction to send_calls.

const approvalCalls = approvalResponse.transactions.map((entry) => ({
  to: entry.transaction.to,
  value: entry.transaction.value ?? "0x0",
  data: entry.transaction.data
}));

Create V3/V4 Position: POST /lp/create

{
  "walletAddress": "<address>",
  "chainId": 8453,
  "protocol": "V4",
  "existingPool": {
    "token0Address": "0x0000000000000000000000000000000000000000",
    "token1Address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "poolReference": "0xe070797535b13431808f8fc81fdbe7b41362960ed0b55bc2b6117c49c51b7eb9"
  },
  "independentToken": {
    "tokenAddress": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000000"
  },
  "tickBounds": {
    "tickLower": -200400,
    "tickUpper": -199200
  },
  "simulateTransaction": false,
  "nativeTokenBalance": "1000000000000000"
}

Use newPool instead of existingPool when creating a pool:

{
  "token0Address": "<address>",
  "token1Address": "<address>",
  "fee": 3000,
  "tickSpacing": 60,
  "initialPrice": "<sqrtRatioX96 string>"
}

Response:

{
  "create": { "to": "...", "data": "...", "value": "...", "chainId": 8453 },
  "token0": { "tokenAddress": "...", "amount": "..." },
  "token1": { "tokenAddress": "...", "amount": "..." },
  "adjustedMinPrice": "...",
  "adjustedMaxPrice": "...",
  "tickLower": -200400,
  "tickUpper": -199200
}

Prefer tickBounds when possible. priceBounds can be accepted by the API, but its price units are easy to misread; validate carefully before using it.

Manage Existing Positions

Optional on LP operation endpoints: "slippageTolerance": <decimal> where 0.5 means 0.5%. See Risks & Warnings before submitting elevated values.

Important: LP APIs can return calldata for syntactically valid nftTokenId values even if the connected wallet may not own the position. Treat generated calldata as a transaction preview input, not proof of ownership or guaranteed execution.

Claim Fees: POST /lp/claim_fees

{
  "protocol": "V4",
  "walletAddress": "<address>",
  "chainId": 8453,
  "tokenId": "<nft token id>",
  "simulateTransaction": false
}

Response:

{
  "claim": { "to": "...", "data": "...", "value": "0x00", "chainId": 8453 },
  "token0": { "tokenAddress": "...", "amount": "..." },
  "token1": { "tokenAddress": "...", "amount": "..." }
}

No approval step is needed for fee collection.

Create V2 Position: POST /lp/create_classic

{
  "walletAddress": "<address>",
  "poolParameters": {
    "token0Address": "0x4200000000000000000000000000000000000006",
    "token1Address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "chainId": 8453
  },
  "independentToken": {
    "tokenAddress": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000000"
  },
  "simulateTransaction": false
}

For V2 create, /lp/check_approval may return multiple approval transactions. Batch all approvals plus the create transaction if you want one send_calls approval link.

Orchestration

Swap orchestration

1. get_wallets -> address; convert tokenIn amount to base units
2. web_request POST /check_approval with x-permit2-disabled
3. web_request POST /quote with x-permit2-disabled
4. Build swapBody from quoteResponse and remove null permit fields
5. web_request POST /swap with x-permit2-disabled
6. send_calls("base", approval + swap calls if approval exists, otherwise swap only)
7. Open the approvalUrl if requested; do not approve unless the user explicitly asks
8. get_request_status only after the user acts

LP orchestration

1. get_wallets -> address
2. For V3/V4 create, call /lp/pool_info to discover poolReference
3. Build LP token amount list in base units
4. web_request POST /lp/check_approval
5. web_request POST /lp/create, /lp/increase, /lp/decrease, /lp/claim_fees, or /lp/create_classic
6. send_calls("base", approval calls + operation call)
7. Open the approvalUrl if requested; do not approve unless the user explicitly asks
8. get_request_status only after the user acts

Submission

Target tool: send_calls (chain "base"). Open the returned approvalUrl only if the user asks, and poll get_request_status after they act (see ../references/approval-mode.md and ../references/batch-calls.md).

Swap send_calls

Approval and swap can be sent separately or batched in one send_calls preview:

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

LP send_calls

For any LP operation response field such as create, increase, decrease, or claim, map to:

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

For approval + action batching:

const operationTx =
  operationResponse.create ??
  operationResponse.increase ??
  operationResponse.decrease ??
  operationResponse.claim;

const calls = [
  ...approvalResponse.transactions.map((entry) => ({
    to: entry.transaction.to,
    value: entry.transaction.value ?? "0x0",
    data: entry.transaction.data
  })),
  {
    to: operationTx.to,
    value: operationTx.value ?? "0x0",
    data: operationTx.data
  }
];

Example Prompts

Swap 1 USDC to WETH on Base

1. get_wallets -> address; use USDC address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913, amount 1000000.
2. web_request POST /check_approval with x-permit2-disabled: true.
3. web_request POST /quote with x-permit2-disabled: true.
4. Remove null permit fields from quote response.
5. web_request POST /swap with x-permit2-disabled: true.
6. send_calls approval + swap, or swap only if no approval was returned.

Create a V4 ETH/USDC LP position on Base

1. get_wallets -> address.
2. web_request POST /lp/pool_info to find the pool reference.
3. web_request POST /lp/check_approval using lpTokens array.
4. web_request POST /lp/create using existingPool.poolReference and tickBounds.
5. send_calls approval transactions plus create transaction.

Add liquidity to an existing V4 position

1. get_wallets -> address.
2. Confirm the wallet owns the nftTokenId or warn that generated calldata may still fail.
3. web_request POST /lp/check_approval with action "INCREASE".
4. web_request POST /lp/increase.
5. send_calls approval transactions plus increase transaction.

Collect LP fees

1. get_wallets -> address.
2. web_request POST /lp/claim_fees with tokenId.
3. send_calls claim transaction.

Risks & Warnings

High slippage tolerance exposes the user to worse fills and sandwich/MEV attacks. Before calling /swap or any LP endpoint with an elevated value, warn the user and get explicit confirmation:

Apply the same thresholds to swap and LP slippage. If the user did not specify a value, prefer autoSlippage: "DEFAULT" on swaps rather than picking a high number.

Notes

• Native ETH address: 0x0000000000000000000000000000000000000000
• USDC on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
• WETH on Base: 0x4200000000000000000000000000000000000006
• Token amounts are base units: USDC = 1e6 per token, ETH/WETH = 1e18 per token.
• Use chain: "base" with send_calls, not numeric chain id.
• For swap proxy approval, include x-permit2-disabled: true on /check_approval, /quote, and /swap.
• For swap proxy approval, remove null permitData and permitTransaction fields before calling /swap.
• /quote response fields must be spread directly into /swap body, not nested under a quote key.
• Do not send signature in the proxy swap flow.