wolfram-debugging

Wolfram Language Debugging

Verified techniques for finding out why Wolfram Language code misbehaves, checked with Wolfram 15.0 in the MCP evaluator (both methods), wolframscript, wolfram -script and the cloud. Many standard techniques silently do nothing in some of these environments, so read the ground rules first. Paths are relative to this skill directory.

Prerequisites

You need a Wolfram kernel. If you have neither of the following, read references/GetWolframEngine.md; to set up the MCP server, read references/SetUpWolframMCPServer.md.

• MCP evaluator (preferred, for example mcp__Wolfram__WolframLanguageEvaluator): a persistent kernel, so definitions made in one call can be inspected in the next.
• wolframscript: a fresh kernel per run, needed for first-time effects (autoloading, package loading) and for Trace where the MCP evaluator cannot run it. -f file.wl prints only Print output; -code '...' drops string quotes (print ToString[expr, InputForm]). Always bound runs: timeout -s KILL 300 wolframscript -f file.wl < /dev/null.

Start here: where does the code run?

Module[{cl = StringRiffle[ToString /@ $CommandLine, " "]},
  <|"Env" -> Which[
      $EvaluationEnvironment === "Script", "wolframscript",
      $EvaluationEnvironment === "WebEvaluation", "CloudEvaluate",
      $EvaluationEnvironment === "WebAPI", "deployed API or remote MCP server",
      StringContainsQ[cl, "ChatbookSandbox"], "MCP Local",
      StringContainsQ[cl, "StartMCPServer"] || StringStartsQ[$Context, "Sessions`"], "MCP Session",
      MemberQ[$CommandLine, "-script"], "wolfram -script",
      True, $EvaluationEnvironment],
    "TraceWorks" -> Trace[1 + 1] =!= {}, "Context" -> $Context, "TimeRemaining" -> Internal`TimeRemaining[]|>]