How to Debug NinjaScript Compile Errors with AI

Pasting compile errors into a chat window almost never converges. The model loses context, fixes the immediate error, breaks something else. With CrossTrade MCP, the agent compiles against the running NT8 AppDomain and reads the structured diagnostic in the same context as the source. Repairs land in two or three iterations.

Direct answer

To repair a compile error with AI through CrossTrade MCP:

1. The agent calls CompileNinjaScript(in_memory: true).
2. Read the diagnostic. Identify the unresolved or mistyped symbol.
3. The agent calls LookupNinjaScriptSymbol on that symbol and rewrites the offending line.
4. Recompile. Repeat until green.

The loop converges because the agent looks at your actual NT8 install, not at training data that may be out of date.

Prerequisites

Requirement	Detail
CrossTrade subscription	Elite
CrossTrade Add-On	v1.13.0 or higher
NinjaTrader 8	Running
MCP client	Claude Code, Cursor, or another client with mcp:trade
Scope	mcp:trade

Common NinjaScript compile errors and the fix pattern

Error	Likely cause	Repair
CS0103 The name 'X' does not exist in the current context	The model invented a symbol or used a removed name	LookupNinjaScriptSymbol(X); rewrite to the correct call
CS1503 Argument N: cannot convert from 'A' to 'B'	Wrong overload chosen	GetNinjaScriptHelp on the method; pick the matching overload
CS1061 'Type' does not contain a definition for 'Member'	Member was renamed or never existed	SearchNinjaScriptSymbols("<member-keyword>"); rewrite
CS0119 'X' is a type, which is not valid in the given context	Type referenced where an instance is needed	Fix the call site; for indicators, instantiate via the helper
CS0246 The type or namespace name 'X' could not be found	Missing using or invented namespace	LookupNinjaScriptSymbol(X) to confirm; if it does not exist, replace with a real type
CS0029 Cannot implicitly convert type 'A' to 'B'	Series vs scalar mismatch	Use [0] to read the current value of a series, or pass the series itself where required

Step 1: Reproduce the error in memory

CompileNinjaScript(in_memory: true) on the current source. Do not write to disk
yet. Report all errors verbatim.

In-memory compile does not affect any file. You can iterate freely.

Step 2: Force a symbol lookup for every unresolved identifier

For every unresolved identifier in the error list, call LookupNinjaScriptSymbol
and tell me the correct shape. Do not rewrite yet.

This is the step that pasted-code workflows skip. Forcing the lookup eliminates guessing.

Step 3: Rewrite the offending lines

Rewrite the offending lines using the overloads you just confirmed. Show me the
diff before recompiling.

Read the diff. If the rewrite changes behavior beyond fixing the compile, push back.

Step 4: Recompile

CompileNinjaScript(in_memory: true). Report success or errors. Do not stop on
warnings; treat warnings as informational.

Repeat steps 2 to 4 until green. Two or three iterations is normal. Persistent failure usually means the spec is ambiguous (the model is guessing at intent), not that it cannot code.

Step 5: Persist the file

Only after a green in-memory compile:

After I confirm, WriteNinjaScriptFile to the same path. Run one more
CompileNinjaScript without in_memory to confirm the disk version compiles too.

When the loop does not converge

If the same identifier keeps failing:

• Force a SearchNinjaScriptSymbols on a synonym.
• Pull a known-good sample (for example, Strategies/SampleMACrossOver.cs) with ReadNinjaScriptFile and have the agent reference the style.
• Re-read the spec with the agent and ask it to restate the intent before rewriting.

If two methods conflict (one fix breaks another file), back up and read the broader context with the agent before continuing.

Troubleshooting

Symptom	Fix
403 insufficient_scope	The compile and write tools need mcp:trade. Reauthorize.
408 timeout	NT8 closed or add-on disconnected. Open NT8.
Same compile error after rewrite	The agent did not actually call LookupNinjaScriptSymbol. Force the lookup.

Related

• Learn: Vibe Code a NinjaScript Strategy
• Learn: Backtest AI-Generated NinjaScript
• Learn: Connect Claude Code
• Docs: CompileNinjaScript
• Docs: LookupNinjaScriptSymbol