Java Debug
Drive IntelliJ-backed debug sessions—breakpoints, stepping, stack traces—for Spring/Java bugs.
Overview
Java Debug is an agent skill most often used in Build (also Ship) that wires agent workflows to IntelliJ Debug MCP for breakpoints, stepping, and runtime inspection of Spring/Java apps.
Install
npx skills add https://github.com/amplicode/spring-skills --skill java-debugWhat is this skill?
- Preflight requires IntelliJ Debug MCP tools (`intellij-debug` / `mcp__intellij-debug__*` prefixes)
- Workflows for breakpoints, stepping (into/over), evaluate expression, and stack traces
- Triggered by EN/RU phrases for crashes, nulls, and unexpected runtime behavior
- Part of Amplicode Spring Agent Toolkit alongside the main Amplicode MCP plugin
Adoption & trust: 1 installs on skills.sh; 54 GitHub stars; 3/3 security scanners passed (skills.sh audits); trending (+100% hot-view momentum).
What problem does it solve?
You see a null, crash, or wrong branch in Spring code and need stepped runtime evidence, not another printf cycle.
Who is it for?
Solo builders on Spring Boot in IntelliJ who already run the Amplicode plugin and Debug MCP.
Skip if: Pure Node/Python projects, headless CI-only environments without IntelliJ, or bugs reproducible only in production without local debug.
When should I use this skill?
User wants to debug, set breakpoints, step through code, evaluate expressions, or investigate runtime crashes/nulls (EN or RU trigger phrases).
What do I get? / Deliverables
The agent uses MCP debug tools to set breakpoints, step, and evaluate expressions, returning stack-backed findings you can fix in code.
- Breakpoint/session guidance
- Stack trace and evaluated expression results
- Root-cause notes tied to repro steps
Recommended Skills
Journey fit
Spans multiple journey phases - primary shelf plus alternate fits below.
Most runtime investigation happens while implementing backend features, before release hardening. Spring/JVM runtime inspection is core backend debugging, especially with the IntelliJ Debug MCP bridge.
Where it fits
Pause on a service method entry to see why a repository returns null during feature development.
Reproduce a failing integration test under the debugger and capture a stack trace before tagging a release.
How it compares
Debugger MCP workflow—not a static stack-trace parser or generic print-debugging checklist.
Common Questions / FAQ
Who is java-debug for?
Indie and small-team Java/Spring developers using Cursor or Claude with Amplicode’s IntelliJ Debug MCP integration.
When should I use java-debug?
In Build while implementing backend features when behavior is wrong at runtime; in Ship during testing when you need to step through failing paths before release.
Is java-debug safe to install?
Debugging can inspect sensitive runtime state; review the Security Audits panel on this page and avoid exposing secrets in evaluated expressions.
SKILL.md
READMESKILL.md - Java Debug
# Preflight: IntelliJ Debug MCP This skill is part of the **Spring Agent Toolkit** and is designed to work with the **IntelliJ Debug MCP server** (provided by the Amplicode IntelliJ plugin alongside the main Amplicode MCP). Before doing anything else, check your tool list for any debug MCP tool — they are exposed under the `intellij-debug` MCP server (e.g. `toggle_breakpoint`, `evaluate_expression`, `get_stack_trace`); harnesses that flatten MCP tools into the tool list use the `mcp__intellij-debug__` prefix on the same names. - **If at least one debug tool is available** — MCP is connected. Proceed with the skill below. - **If none are available** — stop and invoke the **`amplicode-install`** skill (bundled with the Spring Agent Toolkit). It installs the Amplicode plugin and walks the user through the **«Настроить Spring Agent»** welcome-screen button + MCP-client restart. After it completes, the debug MCP tools become available — resume this skill. - If `amplicode-install` is not registered in your skill list, tell the user (in their language): *"This skill needs the Amplicode IntelliJ plugin and its debug MCP server. Install it from https://amplicode.ru/marketplace into IntelliJ IDEA Ultimate/Community or GigaIDE, open any project, click «Настроить Spring Agent» on the Amplicode welcome screen, then restart your MCP client."* --- # Debugging with IntelliJ Debug MCP This skill guides you through debugging applications via the IntelliJ Debug MCP server. The MCP server runs inside IntelliJ IDEA and gives you programmatic control over the debugger. ## SAFETY RULES — Read These First These rules prevent you from hanging indefinitely or losing debugging context. They exist because the debugged application can be **suspended on a breakpoint** at any time, which means it stops responding to all requests. ### The Suspended-Process Trap When the app hits a breakpoint, its threads freeze. Any HTTP request, curl call, or network interaction you make to that app **will hang forever** — the app can't respond until you resume it. This is the single most common mistake. **Rule 1: Always use timeouts when talking to the debugged app.** Use `--max-time 5` with curl, or set `run_in_background: true` on Bash tool calls. Do this even if you just checked that the app is running — it could hit a breakpoint between your check and your request. **Rule 2: Check suspension status before network calls.** Call `list_debug_sessions` and look at `isSuspended`. If the app is suspended, either `resume` it first or accept your request will block. **Rule 3: Always verify position after stepping.** After `step_over`, `step_into`, or `step_out`, call `get_current_position`. Never assume where execution landed — it might have jumped to an unexpected line or even a different file. **Rule 4: Check status after resume.** After calling `resume`, the app may immediately hit another breakpoint. Always call `list_debug_sessions` or `get_current_position` to confirm whether the session is still running or suspended again