Borrowing it
Nothing to install: this file belongs to matteing/opal. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/matteing/opal/main/.claude/skills/debugging/SKILL.mdgit clone --depth 1 https://github.com/matteing/opalWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/matteing/opal/debugging)<a href="https://agentmods.dev/skills/matteing/opal/debugging"><img src="https://agentmods.dev/badge/skills/matteing/opal/debugging/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/matteing/opal/debugging"><img src="https://agentmods.dev/badge/skills/matteing/opal/debugging.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00050 | $0.02010 |
| Opus 5.5 | $0.00020 | $0.00804 |
| Sonnet 5.5 | $0.00010 | $0.00402 |
| Haiku 4.5 | $0.00005 | $0.00201 |
Grade A, and why
debugging scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Debugging Skill
You use the debug_state tool and Opal's runtime introspection to diagnose problems during a session. This skill teaches you when and how to self-diagnose.
When to act
- A tool call fails unexpectedly or returns surprising results.
- The agent seems stuck in a loop or keeps retrying the same action.
- You suspect context is getting large and may be near the token limit.
- A feature (sub-agents, skills) doesn't seem to be working.
- The user asks you to debug yourself or inspect your own state.
The debug feature is disabled by default
The debug_state tool and the in-memory event log are gated behind the debug feature flag, which is off by default. If you try to call debug_state and the tool isn't available, tell the user they need to enable it first.
How the user enables debug mode
From the TUI menu: Press Ctrl+\ (or the configured menu hotkey) to open the Opal Menu, then toggle Debug introspection on. This takes effect immediately for the current session.
From Elixir code:
Opal.start_session(%{
features: %{debug: %{enabled: true}}
})
Via application config:
config :opal,
features: %{debug: %{enabled: true}}
When debug is enabled, Opal keeps an in-memory event log (bounded ring buffer of the last 400 events) and exposes the debug_state tool. When debug is disabled, the event log is cleared and the tool is filtered out of the active tool set.
Using debug_state
Basic snapshot (no messages, no events)
debug_state({})
Returns: session ID, model info, provider, working directory, token usage, tool availability, and queue state.
With recent events
debug_state({"event_limit": 100})
The event_limit parameter controls how many recent events to include (default: 50, max: 500). Events are returned newest-first and include a timestamp, event type, and a truncated data preview.
With conversation messages
debug_state({"include_messages": true, "message_limit": 10})
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 201 lines · 50 tokens per session scan A f80cb9aa9dcd
debugging is a skill published in the GitHub repository matteing/opal (62 stars, last pushed 2mo ago), licensed MIT. It adds 50 tokens to every session and 2,010 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
debugging compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| debuggingmatteing/opal | Skill | 62 | 2mo ago | MIT | A | 50 | Claude Code |
| building-agentsericrisco/rsc-harness | Skill | 503 | 2d ago | MIT | A | 85 | Claude Code, Codex |
| agent-evalericrisco/rsc-harness | Skill | 503 | 2d ago | MIT | A | 79 | Claude Code, Codex |
| code-reviewdamianvtran/local-operator | Skill | 229 | yesterday | MIT | A | 45 | Claude Code, Codex |
| browser-qadamianvtran/local-operator | Skill | 229 | yesterday | MIT | A | 45 | Claude Code, Codex |
| design-qadamianvtran/local-operator | Skill | 229 | yesterday | MIT | A | 50 | Claude Code, Codex |
| engineering-principlesdamianvtran/local-operator | Skill | 229 | yesterday | MIT | A | 42 | Claude Code, Codex |