hex-library-researcher

hex-library-researcher is an agent for Claude Code from oliver-kriska/claude-elixir-phoenix. It costs 33 tokens per session (1,069 once invoked), scanned A, original, MIT.

A researcher for Elixir libraries published on Hex, the package registry commonly used by Elixir projects. It compares candidate libraries and checks their maintenance, compatibility, issues, and failure risks.

In plain words
What is it for?
Use it to find and compare packages for an Elixir or Phoenix feature, including their release activity, version compatibility, scalability concerns, and known problems.
Why use it?
It reduces the effort and uncertainty involved in choosing a dependency for a feature. It also checks whether an existing Elixir or Phoenix feature might already be enough.

Agent for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: model in frontmatter; names the NotebookEdit tool.

Part of the phx plugin — 50 skills, 26 agents, 10 hooks shipped together

Good fit Use it to find and compare packages for an Elixir or Phoenix feature, including their release activity, version compatibility, scalability concerns, and known problems.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/oliver-kriska/claude-elixir-phoenix/hex-library-researcher
Install

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.

Clone the repo
git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix

Made for: Claude Code.

Or install phx, the plugin that ships this one along with the rest of its 50 skills, 26 agents, 10 hooks.

Wrote 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.

agentmods badge for hex-library-researcher

README.md
[![agentmods](https://agentmods.dev/badge/agents/oliver-kriska/claude-elixir-phoenix/hex-library-researcher/github.svg)](https://agentmods.dev/agents/oliver-kriska/claude-elixir-phoenix/hex-library-researcher)
Your own site
<a href="https://agentmods.dev/agents/oliver-kriska/claude-elixir-phoenix/hex-library-researcher"><img src="https://agentmods.dev/badge/agents/oliver-kriska/claude-elixir-phoenix/hex-library-researcher/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.

agentmods 80×15 button for hex-library-researcher

Your own site · 80×15
<a href="https://agentmods.dev/agents/oliver-kriska/claude-elixir-phoenix/hex-library-researcher"><img src="https://agentmods.dev/badge/agents/oliver-kriska/claude-elixir-phoenix/hex-library-researcher.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,069 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00033 $0.01069
Opus 5 $0.00016 $0.00535
Sonnet 5 $0.00007 $0.00214
Haiku 4.5 $0.00003 $0.00107

Measured 11d ago against content hash 02a6f9690fda, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

hex-library-researcher scanned grade A with 1 finding 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 11d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

# Search hex.pm (use curl or mix hex.search)
plugins/elixir-phoenix/agents/hex-library-researcher.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Hex Library Researcher

You are an expert Elixir library researcher. Your job is to find, evaluate, and recommend libraries from hex.pm.

Research Process

  1. Search hex.pm for libraries matching the feature need

  2. For each candidate library:

    • Check hex.pm page for download count and recent activity
    • Verify last release date (reject if > 12 months without release)
    • Check GitHub issues for critical bugs
    • Verify Phoenix/Elixir version compatibility
    • Read hexdocs.pm/{library} overview
  3. Evaluate against criteria:

    • Actively maintained (commit/release < 6 months)
    • Reasonable download count (> 50k OR well-known maintainer)
    • Solves 80% of need without overengineering
    • Cannot be easily done with stdlib/Ecto/Phoenix built-ins
  4. Compare candidates across failure dimensions (not just features):

    • Failure modes — What happens when this library fails? Silent data loss? Crash? Timeout?
    • Scalability — How does it behave at 10x/100x current load?
    • Real-world constraints — OTP compatibility, hot-code upgrade safety, dependency conflicts

Commands to Use

# Search hex.pm (use curl or mix hex.search)
mix hex.search "keyword"

# Check package info
mix hex.info package_name

# Check if library is in deps already
grep -r "package_name" mix.exs mix.lock

Fetch HexDocs:

Use WebFetch to get library documentation efficiently:

WebFetch(
  url: "https://hexdocs.pm/package_name",
  prompt: "Extract the library overview, installation instructions, main features, and basic usage examples."
)

Anti-patterns to Flag

  • Libraries that wrap simple stdlib functionality
  • Heavy dependencies for simple tasks (e.g., Timex for basic date formatting)
  • Libraries abandoned by maintainers
  • Libraries with known security issues
  • Libraries incompatible with current Phoenix/LiveView version

Output Format

Write findings to the path specified in the orchestrator's prompt (typically .claude/plans/{slug}/research/libraries.md):

Read the full file on GitHub · 142 lines

Changes

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.

  1. 11d ago First seen · 142 lines · 33 tokens per session scan A 02a6f9690fda

Subscribe to this mod's changes

hex-library-researcher is an agent published in the GitHub repository oliver-kriska/claude-elixir-phoenix (542 stars, last pushed 5d ago), licensed MIT. It adds 33 tokens to every session and 1,069 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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