Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add rodolfochicone/rc-project/plugin install rcWrote 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/rodolfochicone/rc-project/rc-diagnose)<a href="https://agentmods.dev/skills/rodolfochicone/rc-project/rc-diagnose"><img src="https://agentmods.dev/badge/skills/rodolfochicone/rc-project/rc-diagnose/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/rodolfochicone/rc-project/rc-diagnose"><img src="https://agentmods.dev/badge/skills/rodolfochicone/rc-project/rc-diagnose.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00037 | $0.01848 |
| Opus 5 | $0.00018 | $0.00924 |
| Sonnet 5 | $0.00007 | $0.00370 |
| Haiku 4.5 | $0.00004 | $0.00185 |
Grade A, and why
rc-diagnose 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 10d 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 — 152 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Diagnose
Find out why something behaves the way it does, then — when a change is implied — fix the cause and verify it. Investigation and remediation are one method, not two skills: splitting them meant writing a plan to disk so the other half could read it back, and a plan that survives a handoff is a plan that went stale.
Read $CLAUDE_PLUGIN_ROOT/skills/promoted/rc/references/conventions.md first — it holds Serena
navigation, the .rc resolution, the root-cause-over-workaround rule, the verification-evidence bar,
and the project-memory contract.
The iron law
NO FIX WITHOUT ROOT CAUSE FIRST
A symptom fix is a failure, not a shortcut. This holds especially under time pressure, when the fix looks obvious, and when you have already tried one — those are the conditions that make guessing tempting, and guessing is what turns 20 minutes into an afternoon.
1 — Frame and reproduce
Restate the prompt as the concrete question(s) the work must answer. If it could be read several materially different ways, ask one focused question; otherwise state your interpretation and proceed.
Read the error completely — the full stack trace, line numbers, error codes. It often contains the
answer. Then reproduce: can you trigger it reliably, with what exact steps, every time? Not
reproducible means gather more data, never guess. Check what recently changed — git diff, recent
commits, new dependencies, config, environment differences.
2 — Investigate
Locate the entry points and symbols, then map the slice: callers, callees, interfaces, data structures, and the flow of control and data through them. Trace behavior end to end; never read one file in isolation. Delegate broad recon on unfamiliar areas to parallel read-only subagents, then read the pivotal files yourself in full before concluding.
Ground every claim in a file:line. Read the code that proves a claim — a name is not evidence,
a function may not do what it is called. Separate established fact (backed by a reference) from
inference (your reasoning) and label which is which.
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 10d ago First seen · 152 lines · 37 tokens per session scan A df9df7b33f48
rc-diagnose is a skill published in the GitHub repository rodolfochicone/rc-project (19 stars, last pushed 1mo ago), licensed MIT. It adds 37 tokens to every session and 1,848 once invoked, about $0.0002 per session on Opus 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.
Other skills, from other repositories
investigate
Delegate read-only investigation, debugging, audit, search, or code-understanding tasks to sub-agents; synthesize only from their structured reports.
dx-audit
Audits libraries, CLIs, and SDKs using 38 rules for public contracts, package exports, piped output, errors, and configuration. Use when asked to "audit my CLI", "review my SDK", "make this agent-friendly", or diagnose package type resolution. For agentic product trust use ax-audit; for docs use docs-writing.
taiyi-health
A codebase health review process that samples recently changed production modules and test files, then checks for issues such as duplication, unused code, and unused dependencies.
instance-performance-triage
Answer "the instance is slow" or "my nightly job never ran" from ServiceNow's own telemetry — transaction logs, syslog, systrigger, progress workers, execution trackers — instead of ad-hoc scripts that add to the load.
change-rollback
Undo a change already written to a ServiceNow instance — recover the prior payload from sysupdateversion, write it back without corrupting it, and know which damage update set back-out, Deleted Records, or nothing at all can reverse.
blast-radius
Trace ServiceNow configuration dependencies — what artifacts touch a given field, what calls a script include, table/app-level config inventory. Use before deletes, renames, or refactors.