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 agentmods add instructions/virtuslab/cellar/claude-mdgit clone --depth 1 https://github.com/VirtusLab/cellarWhat 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 | $0.01256 | $0.01256 |
| Opus 5 | $0.00628 | $0.00628 |
| Sonnet 5 | $0.00251 | $0.00251 |
| Haiku 4.5 | $0.00126 | $0.00126 |
Grade A, and why
cellar CLAUDE.md 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 2d 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 — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Important tools
- Cellar
When you need the API of a JVM dependency, always use cellar. Use it before metals-mcp.
Project-aware commands (run from project root)
For querying the current project's code and dependencies (auto-detects build tool):
cellar get [--module <name>] <fqn> # single symbol
cellar list [--module <name>] <package> # explore a package
cellar search [--module <name>] <query> # find by name
- Mill/sbt projects:
--moduleis required (e.g.--module lib,--module core) - scala-cli projects:
--moduleis not supported (omit it) --test: query the test-scope classpath (sbt/scala-cli; for Mill, use the test module directly, e.g.--module foo.test)--no-cache: skip classpath cache, re-extract from build tool--java-home: override JRE classpath
External commands (query arbitrary Maven coordinates)
For querying any published artifact by explicit coordinate:
cellar get-external <coordinate> <fqn> # single symbol
cellar list-external <coordinate> <package> # explore a package
cellar search-external <coordinate> <query> # find by name
cellar deps <coordinate> # dependency tree
Coordinates must be explicit: group:artifact_3:version
Development Principles
- Think Before Coding
Don't assume. Don't hide confusion. Surface tradeoffs.
Before implementing:
State your assumptions explicitly. If uncertain, ask.
If multiple interpretations exist, present them - don't pick silently.
If a simpler approach exists, say so. Push back when warranted.
If something is unclear, stop. Name what's confusing. Ask.
2. Simplicity First
Minimum code that solves the problem. Nothing speculative.
No features beyond what was asked.
No abstractions for single-use code.
No "flexibility" or "configurability" that wasn't requested.
No error handling for impossible scenarios.
If you write 200 lines and it could be 50, rewrite it.
Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.
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.
- 2d ago First seen · 120 lines · 1,256 tokens per session scan A bee5edef6cb6
cellar CLAUDE.md is an instructions file published in the GitHub repository VirtusLab/cellar (87 stars, last pushed 3d ago), licensed MPL-2.0. It adds 1,256 tokens to every session, about $0.0063 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.
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