position.open

Open a position in a prediction market with declarative parameters and automatic risk management.

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Overview

The position.open tool executes trades on prediction markets with built-in risk checks, slippage protection, and approval workflows. Agents describe trade intent using natural language; MoltMarket handles order placement, transaction signing, and position tracking.

Key features:

• Automatic risk limit validation

• Conditional execution (e.g., "if probability < 45%")

• Stop-loss and take-profit configuration

• Hardware wallet approval for large trades

• Transaction confirmation tracking

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Parameters

Parameter	Type	Required	Description
market_id	string	Yes	Platform-specific market identifier
platform	string	Yes	"polymarket" or "kalshi"
side	string	Yes	"YES" or "NO"
amount	number	Yes	Position size in USD/USDC
order_type	string	No	"market" or "limit" (default: market)
limit_price	number	No	Limit price 0-1 (required if order_type=limit)
slippage_tolerance	number	No	Max acceptable slippage in % (default: 1.0)
stop_loss	number	No	Auto-close if price reaches this level (0-1)
take_profit	number	No	Auto-close if price reaches this level (0-1)
conditions	object	No	Conditional execution rules

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Request Examples

Market Order

result = agent.run("""
  Buy $500 YES on presidential election market
  on Polymarket at market price
""")

Limit Order

result = agent.run("""
  Buy $1000 YES on Fed rate cut market at limit price 0.45
  with 2% slippage tolerance
""")

With Risk Management

result = agent.run("""
  Buy $500 YES position with:
  - Stop-loss at 35%
  - Take-profit at 65%
  - Max slippage 1.5%
""")

Conditional Execution

result = agent.run("""
  If presidential market probability < 45%,
  buy $500 YES position
""")

MCP Tool Call (JSON)

{
  "tool": "position.open",
  "parameters": {
    "market_id": "0x1a2b3c4d5e6f...",
    "platform": "polymarket",
    "side": "YES",
    "amount": 500,
    "order_type": "market",
    "slippage_tolerance": 1.5,
    "stop_loss": 0.35,
    "take_profit": 0.65
  }
}

---

Response Format

Successful Execution

{
  "status": "executed",
  "position_id": "pos_9x8y7z6w5v4u",
  "market_id": "0x1a2b3c4d5e6f...",
  "market_title": "Presidential Election 2024",
  "platform": "polymarket",
  "side": "YES",
  "amount": 500,
  "shares": 1063.83,
  "avg_price": 0.47,
  "fees": {
    "platform_fee": 0,
    "network_fee": 2.50,
    "total_fees": 2.50
  },
  "risk_management": {
    "stop_loss": 0.35,
    "take_profit": 0.65,
    "max_loss": 127.66,
    "max_profit": 191.49
  },
  "transaction": {
    "hash": "0x5d6e7f8g9h0i...",
    "block_number": 45678901,
    "timestamp": "2026-03-19T14:32:10Z",
    "confirmations": 3
  },
  "execution_time_ms": 2341
}

Risk Limit Exceeded

{
  "status": "rejected",
  "reason": "risk_limit_exceeded",
  "message": "Position size $500 exceeds daily loss limit",
  "risk_check": {
    "requested_amount": 500,
    "max_position_size": 1000,
    "current_daily_loss": 4800,
    "max_daily_loss": 5000,
    "remaining_budget": 200
  },
  "suggestions": [
    "Reduce position size to $200 or less",
    "Wait until tomorrow for daily limit reset",
    "Increase max_daily_loss in config"
  ]
}

Requires Approval

{
  "status": "pending_approval",
  "reason": "amount_above_threshold",
  "message": "Trade amount $1200 requires hardware wallet approval",
  "approval_request": {
    "market": "Presidential Election 2024",
    "side": "YES",
    "amount": 1200,
    "estimated_shares": 2553.19,
    "estimated_price": 0.47
  },
  "instructions": "Confirm transaction on your Ledger device"
}

---

Risk Validation

Before executing trades, MoltMarket validates:

1. Position Size Limits

# config.yaml
security:
  max_position_size: 1000  # Per-trade limit

Validation:

✓ amount <= max_position_size
✗ Rejected if amount > max_position_size

2. Total Exposure Limits

security:
  max_total_exposure: 10000  # All positions combined

Validation:

✓ (existing_exposure + amount) <= max_total_exposure
✗ Rejected if exceeds total exposure limit

3. Daily Loss Limits

security:
  max_daily_loss: 5000  # Max loss per day

Validation:

✓ current_daily_loss < max_daily_loss
✗ Rejected if daily limit already hit

4. Concentration Limits

risk:
  max_concentration: 0.30  # Max 30% in single market

Validation:

✓ (market_exposure + amount) / total_exposure <= 0.30
✗ Rejected if causes over-concentration

5. Open Position Limits

risk:
  max_open_positions: 20

Validation:

✓ open_positions < 20
✗ Rejected if already at limit

---

Approval Workflows

Small Trades (Auto-Approve)

# Trades < $100 execute automatically
if amount < 100:
    sign_with_session_key()
    broadcast_transaction()

Medium Trades (Notification + Auto-Execute)

# Trades $100-$1000: notify but execute
if 100 <= amount < 1000:
    notify_user(trade_details)
    sign_with_session_key()
    broadcast_transaction()

Large Trades (Hardware Wallet Required)

# Trades >= $1000: require Ledger approval
if amount >= 1000:
    display_on_ledger(trade_details)
    wait_for_user_approval()
    sign_with_ledger()
    broadcast_transaction()

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Order Types

Market Order

Executes immediately at best available price.

Pros:

• Guaranteed execution (if sufficient liquidity)

• Fast (< 2 seconds)

Cons:

• Price uncertainty

• Potential slippage

agent.run("Buy $500 YES at market price")

Limit Order

Executes only at specified price or better.

Pros:

• Price certainty

• Better execution prices

Cons:

• May not fill

• Requires monitoring

agent.run("Buy $500 YES at limit price 0.45")

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Platform-Specific Behavior

Polymarket

Settlement: On-chain USDC on Polygon Gas Fees: ~$0.50-2.50 per trade Collateral: USDC (1:1) Order Book: Continuous (always available)

Example transaction flow:

1. Approve USDC spending (one-time)

2. Submit trade to CLOB API

3. Order matched on-chain

4. Shares minted via CTF contract

5. Position recorded in wallet

Kalshi

Settlement: USD (centralized) Fees: ~2% per trade Collateral: USD (fiat) Order Book: Continuous (market hours)

Example transaction flow:

1. Check USD balance

2. Submit order via REST API

3. Order matched by Kalshi

4. Position recorded in account

5. Confirmation email sent

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Error Handling

Insufficient Balance

{
  "error": "insufficient_balance",
  "message": "Wallet balance $320 insufficient for $500 trade",
  "required": 502.50,  // Including fees
  "available": 320.00,
  "shortfall": 182.50
}

Solution: Deposit more USDC/USD

Slippage Exceeded

{
  "error": "slippage_exceeded",
  "message": "Actual price 0.49 exceeds 1% slippage tolerance",
  "expected_price": 0.47,
  "actual_price": 0.49,
  "slippage": 4.26,
  "tolerance": 1.0
}

Solution: Increase slippage tolerance or use limit order

Market Closed

{
  "error": "market_closed",
  "message": "Market closed for trading at 2024-11-05T23:59:59Z",
  "close_date": "2024-11-05T23:59:59Z",
  "time_closed": "2 hours ago"
}

Solution: Find alternative market

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Performance

Metric	Polymarket	Kalshi
Avg Execution Time	2.1s	1.8s
p95 Execution Time	3.5s	2.9s
Success Rate	98.2%	99.1%
Typical Gas Fee	$1.20	$0 (included in spread)

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Best Practices

1. Always Set Stop-Losses

   agent.run("Buy $500 YES with stop-loss at 35%")

2. Use Limit Orders for Large Trades

   # Better price execution on $1000+ trades
   agent.run("Buy $2000 YES at limit price 0.46")

3. Check Liquidity First

   markets = agent.run("Find markets with > $500K liquidity")
   # Then trade on liquid markets

4. Monitor Slippage

   # For volatile markets, allow higher slippage
   agent.run("Buy $500 YES with 2% slippage tolerance")

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Related Tools

• market.search - Find markets to trade

• position.close - Close existing positions

• portfolio.get_positions - Monitor open positions

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Examples

See Event-Driven Trading for advanced position management.