Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add oliver-kriska/claude-elixir-phoenix --skill phx-tracegit clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenixWrote 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/oliver-kriska/claude-elixir-phoenix/phx-trace)<a href="https://agentmods.dev/skills/oliver-kriska/claude-elixir-phoenix/phx-trace"><img src="https://agentmods.dev/badge/skills/oliver-kriska/claude-elixir-phoenix/phx-trace/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/oliver-kriska/claude-elixir-phoenix/phx-trace"><img src="https://agentmods.dev/badge/skills/oliver-kriska/claude-elixir-phoenix/phx-trace.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 | $0.00036 | $0.00580 |
| Opus 5 | $0.00018 | $0.00290 |
| Sonnet 5 | $0.00007 | $0.00116 |
| Haiku 4.5 | $0.00004 | $0.00058 |
Grade A, and why
phx-trace 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 5d 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 — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Call Tracing
Build call trees showing how functions are reached from entry points.
Iron Laws - Never Violate These
- Always use
mix xref callersfirst - It's authoritative; grep is fallback only - Stop at entry points - Controllers, LiveView callbacks, Oban workers, GenServer callbacks
- Track visited MFAs - Prevent infinite loops from circular calls
- Extract argument patterns - Just knowing "who calls" isn't enough; HOW they call matters
- Max depth 10 - Deeper trees indicate architectural issues, not useful traces
When to Build Call Tree (Use Proactively)
| Condition | Why Call Tree Helps |
|---|---|
| Unexpected nil/value at runtime | Trace where the value originates |
| Bug can't reproduce locally | See all entry points that reach the code |
| Changing function signature | Find all callers and their argument patterns |
| Incomplete stack trace | Get full path context |
| "Where does X come from?" | Visual answer to data flow question |
Quick Trace
Run the caller query first, then inspect another function in the chain as needed:
mix xref callers MyApp.Accounts.update_user/2
mix xref callers MyApp.Accounts.get_user/1
Read the reported locations to see argument patterns.
Entry Points (Stop Here)
| Pattern | Type |
|---|---|
def mount/3, def handle_event/3 |
LiveView |
def index/2, def show/2, def create/2 |
Controller |
def perform(%Oban.Job{}) |
Oban Worker |
def handle_call/3, def handle_cast/2 |
GenServer |
Full Recursive Trace
Trace controller, LiveView, worker, and internal entry-point categories in this
session, starting each category with mix xref callers. Native generic workers
may handle independent categories in parallel when the runtime provides them,
but the same-session sequential path is fully supported and must produce the
same call tree. Do not require a named custom agent or Claude-specific spawn
configuration.
Output Location
What ships with it
3 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.
- 5d ago First seen · 69 lines · 36 tokens per session scan A 4248059466fb
phx-trace is a skill published in the GitHub repository oliver-kriska/claude-elixir-phoenix (541 stars, last pushed 3d ago), licensed MIT. It adds 36 tokens to every session and 580 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 2026-09-03.
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