build_add_liquidity_tx
Build an unsigned transaction to add liquidity to a prediction market. Requires prior stablecoin approval. Returns LP tokens.
LABSCO SUMMARY
The agent can do everything up to the signature, and nothing past it.
Trading servers usually ask for a private key. This one draws the line at building the transaction: research, balances, allowances and the encoded call all happen automatically, and the irreversible step stays with you.
What it is
A server over GuessMarket, a prediction market live on Ethereum, Base, Polygon, BSC and PulseChain. It splits cleanly in two: reads that come from the API or straight off-chain over public RPC, and builders that return unsigned EVM transactions. The server never holds a key — you sign and broadcast.
What you get
- Markets listed with filters on status and chain, and any single market's question, YES/NO odds, volume, liquidity and end time
- Price history as timestamped points, for trend work and charting
- The chains it is deployed on, with the MarketFactory, FeeManager and oracle addresses
- A wallet's trading activity across every market, its stablecoin balance, its share and LP holdings on a market, and how much a market is approved to spend
- Unsigned transactions to approve spending, buy or sell YES/NO shares, add or remove liquidity, claim winnings from a resolved market, and create a market
- A combined approve-and-buy builder that returns two ordered transactions instead of one round trip
- Contract ABIs, for building anything the shaped calls do not cover
Requirements
A wallet you sign with — every trading call returns an unsigned transaction, so nothing moves without your signature. The on-chain reads go through public RPC endpoints and need no API key. Amounts are human-readable and converted to the right decimals per chain, including the stablecoins that use different decimals depending on which chain they are on.
Setup effort
One command — npx -y guessmarket-mcp
USE CASES
01
Finding a market worth an opinion
List the active markets on the chain you use, then read the one that interests you — odds, volume, liquidity and when it closes.
02
Deciding whether the odds have already moved
Pull the timestamped price history and look at the trend before the current number.
03
Checking you can actually place the trade
Read the wallet's stablecoin balance and what the market is already approved to spend.
04
Buying a position in one pass
Take the approve-and-buy pair as two ordered transactions, or build the approval and the buy separately if you prefer to see them apart.
05
Taking money off the table
Read the position, then build the sale, or claim the winnings once the market has resolved.
06
Providing liquidity, or opening a market of your own
Add or withdraw liquidity against a market, or create a new one through the MarketFactory with the question and end time you set.
17 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
build_approve_tx
Build an unsigned ERC-20 approve transaction to let a prediction market spend your stablecoin. Must be signed and broadcast before buying shares or adding liquidity.
build_buy_shares_tx
Build an unsigned transaction to buy YES or NO shares on a prediction market. Requires prior stablecoin approval. Returns shares based on CPMM pricing.
build_buy_with_approval_tx
Build TWO unsigned transactions: (1) approve stablecoin spending and (2) buy shares. Convenience tool that combines approve + buyShares. Both must be signed and sent in order.
build_claim_winnings_tx
Build an unsigned transaction to claim winnings from a resolved prediction market. Only works after the market has been resolved. Returns stablecoin.
build_create_market_tx
Build an unsigned transaction to create a new prediction market via the MarketFactory. Returns the address of the new market contract in the transaction receipt.
build_remove_liquidity_tx
Build an unsigned transaction to remove liquidity from a prediction market. Burns LP tokens and returns stablecoin.
build_sell_shares_tx
Build an unsigned transaction to sell YES or NO shares on a prediction market. Returns stablecoin based on CPMM pricing.
get_abi
Get the ABI (Application Binary Interface) for a GuessMarket smart contract. Use this to build transactions for on-chain trading. Valid contracts: PredictionMarket, MarketFactory, ERC20, FeeManager, Oracle, SimpleOracle.
get_allowance
Check how much stablecoin a prediction market contract is approved to spend from a wallet. Use this before buying shares to see if an approve transaction is needed.
get_balance
Get a wallet's stablecoin (USDC/USDT) balance on a specific chain. Returns balance in both raw and human-readable format.
get_market
Get detailed info for a single prediction market by its contract address. Returns question, current YES/NO odds, volume, liquidity, end time, resolution status, and chain.
get_market_history
Get price history for a market. Returns timestamped YES/NO price data points for charting and trend analysis. Optionally specify chain_id and limit.
get_networks
Get all blockchain networks GuessMarket is deployed on, with contract addresses (MarketFactory, FeeManager, Oracle, Stablecoin) for each chain. Essential for on-chain trading.
get_portfolio
Get a wallet's trading activity across all GuessMarket markets. Returns trades with market address, outcome, shares, cost, and timestamp.
get_position
Get a wallet's share holdings on a specific prediction market. Returns YES shares, NO shares, and LP tokens.
list_markets
List prediction markets on GuessMarket. Filter by status (active/resolved/all) and chain_id. Returns market address, question, odds, volume, and end time.
BEFORE YOU INSTALL
What to know first
Tools you get
17 tools when we connected.
Requires
- npx on PATH
- Node.js 18 or later
CONTEXT COST
Light Standing cost
Rated by the size of the 17 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Add the block to your client, or run the command directly.
Server setup
Configuration file
JSON
{
"mcpServers": {
"guessmarket-mcp": {
"command": "npx",
"args": [
"-y",
"guessmarket-mcp"
]
}
}
}npx
TERMINAL
npx -y guessmarket-mcp
