Borrowing it
Nothing to install: this file belongs to cel-expr/skills. 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/cel-expr/skills/main/CLAUDE.mdgit clone --depth 1 https://github.com/cel-expr/skillsWrote 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/instructions/cel-expr/skills/claude-md)<a href="https://agentmods.dev/instructions/cel-expr/skills/claude-md"><img src="https://agentmods.dev/badge/instructions/cel-expr/skills/claude-md/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/instructions/cel-expr/skills/claude-md"><img src="https://agentmods.dev/badge/instructions/cel-expr/skills/claude-md.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 | $0.00855 | $0.00855 |
| Opus 5.5 | $0.00342 | $0.00342 |
| Sonnet 5.5 | $0.00171 | $0.00171 |
| Haiku 4.5 | $0.00085 | $0.00085 |
Grade A, and why
skills 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 yesterday.
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 — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Common Expression Language (CEL) Skills
This repository provides tools and skills to author, test, debug, and optimize Common Expression Language (CEL) expressions.
Project Structure & Architecture
cmd/cel-expr: Unified CLI and MCP server entry point (cel-expr).cmd/mcp: Standalone entry point for the Model Context Protocol (MCP) server (cel-expr-mcp).internal/mcp: MCP server implementation, transport setup, and tool dispatch.internal/tools: Internal implementation for environment loading, compilation, evaluation, coverage, and prompt generation.skills/: Agent skills directory containing guidelines and workflows:cel-authoring: Authoring, configuring, and testing expressions and JSON environment definitions.cel-debugging: Diagnosing and resolving compilation and evaluation errors.cel-testing: Testing and validating expressions against test cases.cel-optimize: Optimizing and simplifying expressions and formally proving semantic equivalence using the CEL-Java Verifier.cel-conformance-testing: Authoring, evaluating, and publishing CEL conformance tests using the cel-spec textproto format.
Build and Test Commands
Go CLI
- Build unified CLI:
go build ./cmd/cel-expr - Build MCP server:
go build ./cmd/mcp - Run tests:
go test ./... - Run unified CLI:
go run ./cmd/cel-expr <compile|eval|env|prompt|mcp> - Run MCP server:
go run ./cmd/mcp
Bazel
- Build all targets:
bazel build //... - Run all tests:
bazel test //...
Provided Tools
The cel-expr-mcp MCP server provides the following tools for AI agents:
cel_create_environment: Defines the variables, functions, and types for a CEL expression environment.cel_generate_prompt: Generates an authoring prompt for a CEL expression based on the configuration and requirement.cel_compile: Compiles a CEL expression to validate syntax, correctness, and type checking against an environment definition.cel_evaluate: Evaluates a compiled expression against provided test cases.cel_evaluate_conformance: Evaluates CEL conformance tests from a cel-spec textproto file or inline content.
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.
- yesterday Changed · +6 lines · +64 tokens per session 4480e444d212
- 12d ago Changed · +8 lines · +117 tokens per session ae563b7a19b5
- 21d ago Changed · +6 tokens per session 121425563b26
- 1mo ago First seen · 73 lines · 668 tokens per session scan A 47fabe4ba717
skills CLAUDE.md is an instructions file published in the GitHub repository cel-expr/skills (2 stars, last pushed 2d ago), licensed Apache-2.0. It adds 855 tokens to every session, about $0.0034 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 2026-08-31.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.