How to Connect Windsurf to NinjaTrader 8 with CrossTrade MCP

Windsurf is Codeium's AI-native IDE. Its Cascade Agent supports MCP servers, which means CrossTrade tools become available alongside your normal code completion in a single editor. The config uses serverUrl (or url) — both accepted, but stick with serverUrl to match Windsurf's official examples.

OAuth scope: mcp:tradeMulti-model harness

Prerequisites

Requirement	Detail
CrossTrade subscription	Elite
CrossTrade NT8 Add-On	v1.13.0 or higher
NinjaTrader 8	Running, broker connected
Account	Sim101 for first runs
OAuth scope	`mcp:trade`
Config file	`~/.codeium/windsurf/mcp_config.json`

CrossTrade MCP server

https://app.crosstrade.io/v1/api/mcp

Transport: streamable-http. Auth: OAuth 2.1 + PKCE. Request scope mcp:trade. Read plus write. Place/cancel orders, deploy strategies, compile NinjaScript.

Step 1: Open Cascade settings

The connection path from Windsurf to a NinjaTrader 8 account. The client speaks the Model Context Protocol to the CrossTrade MCP server, which is hosted rather than local. Authorisation happens once over OAuth and issues a scoped token. From there the server calls through to the CrossTrade NT8 Add-On inside your running NinjaTrader, and results travel back the same way as plain language. — Four hops, authorised once. Read-only is the scope to start with.

Open Windsurf → Cascade panel → MCP Servers → Add server.

Or edit ~/.codeium/windsurf/mcp_config.json directly:

{
  "mcpServers": {
    "crosstrade": {
      "serverUrl": "https://app.crosstrade.io/v1/api/mcp",
      "headers": {
        "Authorization": "Bearer ${env:CROSSTRADE_TOKEN}"
      }
    }
  }
}

serverUrl vs url

Windsurf accepts both serverUrl and url. The official docs example uses serverUrl — use that to avoid surprises if Windsurf ever drops the alias. Variable interpolation: ${env:VAR_NAME}, ${file:/path/to/file}.

Step 2: OAuth

Per Windsurf's docs: "Windsurf supports OAuth for each transport type." Reload Cascade. First tool call triggers the browser OAuth flow.

Step 3: NinjaScript loop

Same compile-loop pattern as Cursor:

GetNinjaScriptHelp on planned types.
Draft into the workspace file.
CompileNinjaScript(in_memory: true).
Repair.
WriteNinjaScriptFile.
RunStrategyBacktest.

Windsurf's strength is multi-step task planning. Phrase the prompt as a single goal ("Build, compile, and backtest a working MES EMA cross strategy on Sim101") and let Cascade plan the steps.

FAQ

Plan requirements?

Windsurf has Free, Pro, Max, Teams, and Enterprise tiers. MCP support is available across them; provider model access scales with tier.

Which transports work?

stdio, SSE, and Streamable HTTP. For CrossTrade, just provide serverUrl and Windsurf auto-detects.

OAuth handshake

The first tool call surfaces an authorization URL. Open it in a browser, approve mcp:trade, and return to the harness. The access token is stored by the harness (keychain, config file, or memory depending on the client).

See CrossTrade MCP OAuth for the full flow, and 403/408 troubleshooting if the handshake fails.

Verify the connection

Smoke-test before doing anything stateful:

Call GetMcpCapabilities and McpSelfTest. Then ListAccounts and GetConnections.
Report add-on version, NT8 version, and which accounts are linked.

If you authorized mcp:trade, also confirm Sim101 is the default account before any order placement.

Funded-account safety

The mcp:trade scope grants order placement. The scope does not protect a funded account; your prompt and account selection do. Default to Sim101 during setup. For funded accounts, verify the firm's automation policy first.

Troubleshooting

Symptom	Likely cause	Fix
403 insufficient_scope	Token authorized at mcp:read but tool requires mcp:trade	Reauthorize the connection and select mcp:trade
OAuth callback fails	System browser blocked the redirect or popup	Copy the auth URL manually, complete it, paste the code back
Tools list is empty after connect	Server registered but session did not refresh	Restart the harness or trigger a tool list refresh
Add-on offline error	NT8 not running, or add-on not loaded	Confirm NT8 is open and the CrossTrade NT8 add-on (v1.13.0+) is installed
Re-auth fails after token expiry	Browser auth state stuck	Restart Windsurf to reset state, then re-authorize
serverUrl ignored	Older Windsurf build	Update Windsurf to current 1.x release; both serverUrl and url are accepted in current versions

Prerequisites

Step 1: Open Cascade settings​

Step 2: OAuth​

Step 3: NinjaScript loop​

FAQ​

Plan requirements?​

Which transports work?​