| name | julia-evaluation |
| description | Activates when user asks to run, evaluate, or test Julia code in a persistent REPL session, or mentions Julia REPL, Julia session, or hot-reloading Julia changes. |
| version | 0.7.1 |
Julia REPL — Behavioral Rules
Use the MCP tools (eval, reset, pkg, activate, session, revise, log_viewer, info) for interactive Julia work. Prefer julia script.jl via bash for one-shot scripts.
Before Every Eval
Always display code in a readable julia code block BEFORE calling eval. The MCP permission prompt shows code as an escaped string which is unreadable.
After Eval
MCP tool results are collapsed in Claude Code. For visual output (plots, heatmaps), tell the user to expand the tool result (Ctrl+O) to see it with full color — do NOT paste ANSI art into your message (it loses colors and streams token-by-token). For structured text (tables, matrices, DataFrames), paste in a fenced code block. Do not paste simple scalars or errors.
Revise vs Reset
Prefer revise — it preserves session state. Only reset when required.
| Change | Action |
|---|
| Function/method body or signature | revise(action="revise") |
| Struct layout (Julia < 1.12) | reset required |
| Corrupted state / stuck code | reset required |
After editing .jl files, call revise(action="revise") to hot-reload (a PostToolUse hook reminds you after .jl edits).
Error Recovery
| Error | Fix |
|---|
UndefVarError | Re-run definition or check spelling |
MethodError | Check argument types |
LoadError | pkg(action="add", packages="...") |
cannot redefine | reset (struct layout change) |
| Hung/infinite | eval(code=..., timeout=5) or reset |
First Use
On first Julia use in a conversation, ask which environment to activate (current directory, specific path, or global).
Capabilities
- Sessions persist variables, functions, and packages across evals
- Multiple named sessions provide isolated workers
timeout parameter kills hung code and respawns the workermax_output prevents context overflow from large resultsisolated=true evals in a fresh module without polluting Mainephemeral=true evals in a disposable temporary session
