# How should an AI agent paper trade before going live?

A connector can already put a broker account inside Claude, ChatGPT, or Grok, and the click that approves an order is only a floor. Paper is the stage where the agent sends that order into the broker's simulator and you read every fill before a live key is in use. You move to live only when a written exit checklist is met (reviewed paper orders, zero checker rejects in the last N sessions, every fill reconciled), and that checklist is not a P&L target.

Paste an order your agent proposed in paper into the [Agent Order Check](/check?utm_source=site&utm_campaign=paper-guide) and see which checks fail. It runs in your browser. Nothing you paste is stored.

Checked on 2026-10-17. No business relationship with these companies. The tastytrade sandbox row was checked on 2026-10-20.

The [broker connectors](/guides/broker-ai-connectors) page lists official connectors for Claude, ChatGPT, and Grok. Approving an order on those connectors is the floor this page starts from.

## The four stages

Research, then propose, then paper, then live. The agent does not skip a stage because a connector is already installed. The ladder is the [Agentic Trading skill](/skills/agentic-trading). The [Desk Kit](/desk-kit) install writes the live flag off.

| Stage | What the agent does | What you do |
| --- | --- | --- |
| Research | Reads and summarizes. | You decide what is worth a plan. Nothing is an order. |
| Propose | Drafts the order: symbol, side, size, type, price, time in force, and max loss. | You approve, edit, or kill the draft. The agent does not send. |
| Paper | Sends the order to the broker paper or sim account in the table below. | You review every fill against the order you approved. |
| Live | Sends only inside limits stored in a file it cannot write. | You hold the kill switch. LIVE_TRADING stays off until you arm it. |

## What must be true to leave paper

You write the exit checklist, and you pick the numbers: how many paper orders you will review, how many sessions in a row the checker must accept, and that every fill is reconciled. The [paper-to-live gate](/skills/paper-live-gate) reads the count you wrote. If N is missing it says NEED RULE, and it does not borrow a number from another page. ELIGIBLE FOR REVIEW is a note for you. It is not permission to send.

Example lines you can write, with your own numbers:

- A minimum number of paper orders you reviewed.
- Zero orders the checker had to reject in the last N sessions.
- Every fill reconciled to the broker's order record.

The checklist is not a P&L target. The [paper-to-live gate](/skills/paper-live-gate) says a paper log is not a forecast of a live result. The Agentic Trading skill has its own graduation counts. Do not copy those counts onto this flag. If you did not write N, the gate says NEED RULE.

Hard limits sit in a file the agent cannot write. The [guardrails guide](/guides/ai-agent-trading-guardrails) is that file and the reject list. The Desk Kit install writes `LIVE_TRADING: off` and `PAPER_FLAG: DISARMED` on the first two lines of limits.md. A seat does not change either line. You hold the kill switch. The guardrails example names it `KILL_SWITCH: operator`.

## How paper works at each broker

Each row is a broker this site already covers, and only where that broker's own page states the fact. Alpaca's row is Alpaca's documentation. This site did not run an Alpaca paper order.

| Broker | Paper environment | How the agent points at it | What paper does not simulate | Source | Checked |
| --- | --- | --- | --- | --- | --- |
| TradeStation | Simulator (SIM). The SIM vs LIVE page calls it a Simulator API for paper trading: fake trading accounts seeded with fake money, and simulated executions with instant fills. | Point the API at https://sim-api.tradestation.com/v3. The live base URL on that page is https://api.tradestation.com/v3. The TradeStation MCP product page does not mention a simulator. | The SIM page says fills are instant. Queue position, slippage, partial fills, borrow, and after-hours are not documented on that page. | [TradeStation SIM vs LIVE](https://api.tradestation.com/docs/fundamentals/sim-vs-live/), [TradeStation MCP](https://www.tradestation.com/platforms-and-tools/mcp/) | Checked on 2026-10-17. |
| Alpaca | Paper trading. A paper-only account trades in that environment only. The paper page says a paper-only account is only entitled to IEX market data. | Use the paper API keys and set APCA_API_BASE_URL to https://paper-api.alpaca.markets. On the MCP, ALPACA_PAPER_TRADE defaults to true. Live is that flag set to false, with live keys. This site did not run an Alpaca paper order. | The paper page says paper does not account for market impact, information leakage, price slippage from latency, queue position on a non-marketable limit, price improvement, regulatory fees, or dividends. Borrow fees are marked coming soon on paper. Short selling is marked available. Order size is not checked against the national best bid and offer size. When a fill is allowed, paper partial-fills a random size 10% of the time. A non-marketable buy limit waits until the limit is at or above the best ask. A sell limit waits until it is at or below the best bid. Premarket and after-hours are marked available on paper, so after-hours is not a missing session on that page. | [Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading), [Alpaca MCP](https://docs.alpaca.markets/us/docs/alpaca-mcp-server) | Checked on 2026-10-17. |
| Webull | uat. The Local MCP page calls it sandbox. The project env example comments that the uat default is paper trading, and that prod is for live trading. | Set WEBULL_ENVIRONMENT to uat. The parameter table default is uat. The Cursor, Claude Desktop, and Kiro examples on the Local MCP page set prod. | Queue position, slippage, partial fills, borrow, and after-hours are not documented on the Local MCP page or in the env example. | [Webull Local MCP](https://developer.webull.com/apis/docs/AI-friendly-Resources/local-mcp), [Webull env example](https://github.com/webull-inc/webull-openapi-mcp/blob/main/.env.example) | Checked on 2026-10-17. |
| QuantConnect | QuantConnect Paper Trading. Live data goes in, the capital is fictional, and the fills are simulated. No brokerage account is required. | On Deploy Live, choose Paper Trading as the brokerage. If the algorithm does not set a brokerage model, paper uses DefaultBrokerageModel. | The paper page says orders through DefaultBrokerageModel do not experience slippage in backtests or paper trading. The slippage page says that model uses NullSlippageModel, which is zero slippage. Market orders fill immediately and completely. When a bid and ask are available, those prices are used for the fill. Queue position, stock borrow, and after-hours are not documented on the paper page. Buying power and margin calls are modeled. The fills page says the pre-built models assume orders completely fill in a backtest. That sentence is about backtests. | [QuantConnect paper](https://www.quantconnect.com/docs/v2/cloud-platform/live-trading/brokerages/quantconnect-paper-trading), [QuantConnect slippage](https://www.quantconnect.com/docs/v2/writing-algorithms/reality-modeling/slippage/key-concepts), [QuantConnect fills](https://www.quantconnect.com/docs/v2/writing-algorithms/reality-modeling/trade-fills/key-concepts) | Checked on 2026-10-17. |
| TradersPost | TradersPost paper broker. The page calls it a basic paper account, separate from a broker's own simulator. | Connect the TradersPost paper broker in the platform. An API host for that broker is not documented on the paper page. Reset is a button beside the broker. It clears balances, orders, and positions. | Market hours are not respected, and orders fill at all hours. A limit fills at any price you name. A market order fills at the midpoint of the bid and the ask by default. Option and futures positions do not expire off the book. Queue position, partial fills, and borrow are not documented on that page. | [TradersPost paper](https://docs.traderspost.io/docs/learn/platform-concepts/paper-trading) | Checked on 2026-10-17. |
| tastytrade | Sandbox. The [sandbox docs](https://developer.tastytrade.com/docs/sandbox/) say it is "a full copy of the tastytrade API backed by simulated money" and that orders "never reach a real market." The same page says "The sandbox does not simulate a real order book. Fill behaviour is derived from the order type and price, and nothing else." A market order "Always fills, at a price of $1." A limit priced under $3 "Fills immediately." A limit priced $3 or above "Goes Live and never fills." | Set TASTYTRADE_ENV to sandbox. Unset means production, and the MCP docs say every order there moves real money. The sandbox docs say sandbox credentials "are a different OAuth application from production." | The same page says "Because fills are synthetic, sandbox positions, balances and transaction history are only useful for exercising the shape of your code. They are not a simulation of trading outcomes." "Market data is not served." The environment "resets every 24 hours," clearing "trades, transactions and positions." Borrow and after-hours are not named on that page. | [tastytrade sandbox](https://developer.tastytrade.com/docs/sandbox/), [tastytrade MCP](https://developer.tastytrade.com/docs/sdks-and-tools/mcp-server/) | Checked on 2026-10-20. |
| eToro | Demo. The Claude guide says to start with demo when you are learning. It does not describe how demo fills. | An endpoint or account switch is not documented. The guide says start with demo. | Queue position, slippage, partial fills, borrow, and after-hours are not documented on the Claude guide. | [eToro Claude guide](https://mcp.etoro.app/claude) | Checked on 2026-10-17. |

Interactive Brokers, Public, Axi, and Webull Cloud are not in the table. The [broker connectors](/guides/broker-ai-connectors) rows quote the official pages and record no paper or sim fill model: [Interactive Brokers](https://www.interactivebrokers.com/en/trading/ai-integrations.php), [Public](https://public.com/mcp-trading), [Axi](https://www.axi.com/int/trading-platforms/mcp), and [Webull Cloud](https://developer.webull.com/apis/docs/AI-friendly-Resources/mcp). A missing row is not a claim that the firm has no simulator. TradingView is not in the table: an alert is not an order.

Broker pages: [TradeStation](/guides/ai-agents-for-tradestation), [Alpaca](/guides/ai-agents-for-alpaca), [QuantConnect](/guides/ai-agents-for-quantconnect), [TradersPost](/guides/ai-agents-for-traderspost-webhooks), [Webull MCP setup](/guides/webull-mcp-setup).

## Paper traps

### A limit fills that would have waited live

Alpaca's paper page fills a non-marketable limit once the price is at the national best bid or offer, and it does not check your size against that quote's size. Queue position is on the list of things paper does not account for. TradersPost's own paper broker fills a limit at any price you name. tastytrade's sandbox docs say a limit priced under $3 "Fills immediately." A limit priced $3 or above "Goes Live and never fills." The page says "Fill behaviour is derived from the order type and price, and nothing else." ([Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading), [TradersPost paper](https://docs.traderspost.io/docs/learn/platform-concepts/paper-trading), [tastytrade sandbox](https://developer.tastytrade.com/docs/sandbox/))

### Partials are missing, or they are random

TradeStation's SIM page says fills are instant and does not document a partial fill. Alpaca's paper page partial-fills a random size 10% of the time when a fill is allowed, which is not a model of the queue. QuantConnect's paper page says the default model fills market orders immediately and completely. Its fills page says the pre-built models assume a complete fill in a backtest. ([TradeStation SIM vs LIVE](https://api.tradestation.com/docs/fundamentals/sim-vs-live/), [Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading), [QuantConnect paper](https://www.quantconnect.com/docs/v2/cloud-platform/live-trading/brokerages/quantconnect-paper-trading), [QuantConnect fills](https://www.quantconnect.com/docs/v2/writing-algorithms/reality-modeling/trade-fills/key-concepts))

### The paper log can vanish, or it is not yours alone

TradersPost's reset button clears balances, orders, and positions. tastytrade's sandbox "resets every 24 hours," "clearing trades, transactions and positions." Alpaca's paper page says the dashboard now creates and deletes paper accounts, and a new account needs new API keys. A checklist that lived only inside that account does not survive the reset. ([TradersPost paper](https://docs.traderspost.io/docs/learn/platform-concepts/paper-trading), [tastytrade sandbox](https://developer.tastytrade.com/docs/sandbox/), [Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading))

### The paper book does not keep the live clock

TradersPost's paper broker does not respect market hours. Orders fill at all hours, including when the live market is closed. Alpaca's comparison table marks premarket and after-hours as available on paper, so this trap is not an Alpaca claim. TradeStation's SIM page does not say whether the simulator keeps equity extended hours. That cell is not documented there. ([TradersPost paper](https://docs.traderspost.io/docs/learn/platform-concepts/paper-trading), [Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading), [TradeStation SIM vs LIVE](https://api.tradestation.com/docs/fundamentals/sim-vs-live/))

### Costs the paper book leaves out

Alpaca's paper page does not account for market impact, latency slippage, price improvement, regulatory fees, or dividends, and borrow fees are marked coming soon. Short selling itself is marked available. QuantConnect's default paper model uses zero slippage. Stock borrow on QuantConnect paper is not documented on the paper page. Buying power and margin calls are modeled there. ([Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading), [QuantConnect paper](https://www.quantconnect.com/docs/v2/cloud-platform/live-trading/brokerages/quantconnect-paper-trading), [QuantConnect slippage](https://www.quantconnect.com/docs/v2/writing-algorithms/reality-modeling/slippage/key-concepts))

### The quote is not the tape you will trade live

A paper-only Alpaca account is only entitled to IEX market data. tastytrade's sandbox docs say "Market data is not served." TradeStation's SIM page does not document the quote feed. ([Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading), [tastytrade sandbox](https://developer.tastytrade.com/docs/sandbox/), [TradeStation SIM vs LIVE](https://api.tradestation.com/docs/fundamentals/sim-vs-live/))

## Questions people ask

### How should an AI agent paper trade before going live?

A connector can already put a broker account inside Claude, ChatGPT, or Grok, and the click that approves an order is only a floor. Paper is the stage where the agent sends that order into the broker's simulator and you read every fill before a live key is in use. You move to live only when a written exit checklist is met (reviewed paper orders, zero checker rejects in the last N sessions, every fill reconciled), and that checklist is not a P&L target.

### What has to be true before the agent trades live?

You write the exit checklist, and you pick the numbers: how many paper orders you will review, how many sessions in a row the checker must accept, and that every fill is reconciled. The [paper-to-live gate](/skills/paper-live-gate) reads the count you wrote. If N is missing it says NEED RULE, and it does not borrow a number from another page. ELIGIBLE FOR REVIEW is a note for you. It is not permission to send.

### Does approving every order replace paper?

No. The [guardrails guide](/guides/ai-agent-trading-guardrails) calls that click a floor. It can stop an order the agent would have sent alone. It does not tell you whether the paper fill would have stood in a live queue, or which host the order used. You still review every paper fill.

### What does a paper fill leave out?

Read the table on this page. Alpaca's paper page leaves out queue position, latency slippage, market impact, price improvement, regulatory fees, dividends, and borrow fees. TradeStation's SIM page documents instant fills and does not document queue, slippage, partials, borrow, or after-hours. QuantConnect's default paper model uses zero slippage and fills market orders completely. A cell that is not on the source says not documented.

### Where do the limits and the kill switch live?

In a file you write. The agent does not write it. The Desk Kit install writes LIVE_TRADING: off and PAPER_FLAG: DISARMED, and a seat does not change either line. You hold the kill switch. [validate_limits.py](/packs/desk-kit/validate_limits.py) reads max loss, live trading, and human approval from that file only.

## Sources checked

Checked on 2026-10-17.

- [TradeStation SIM vs LIVE](https://api.tradestation.com/docs/fundamentals/sim-vs-live/)
- [TradeStation MCP](https://www.tradestation.com/platforms-and-tools/mcp/)
- [Alpaca paper trading](https://docs.alpaca.markets/us/docs/paper-trading)
- [Alpaca MCP](https://docs.alpaca.markets/us/docs/alpaca-mcp-server)
- [Webull Local MCP](https://developer.webull.com/apis/docs/AI-friendly-Resources/local-mcp)
- [Webull env example](https://github.com/webull-inc/webull-openapi-mcp/blob/main/.env.example)
- [QuantConnect paper](https://www.quantconnect.com/docs/v2/cloud-platform/live-trading/brokerages/quantconnect-paper-trading)
- [QuantConnect slippage](https://www.quantconnect.com/docs/v2/writing-algorithms/reality-modeling/slippage/key-concepts)
- [QuantConnect fills](https://www.quantconnect.com/docs/v2/writing-algorithms/reality-modeling/trade-fills/key-concepts)
- [TradersPost paper](https://docs.traderspost.io/docs/learn/platform-concepts/paper-trading)
- [tastytrade sandbox](https://developer.tastytrade.com/docs/sandbox/)
- [tastytrade MCP](https://developer.tastytrade.com/docs/sdks-and-tools/mcp-server/)
- [eToro Claude guide](https://mcp.etoro.app/claude)
- [Broker connectors](/guides/broker-ai-connectors)
- [Guardrails](/guides/ai-agent-trading-guardrails)
- [Paper-to-live gate](/skills/paper-live-gate)
- [Agentic Trading skill](/skills/agentic-trading)

Educational only. Not financial advice.

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