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 agents/thrashr888/agentkernel/codexgit clone --depth 1 https://github.com/thrashr888/agentkernelWhat 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 | $0.00000 | $0.00651 |
| Opus 5 | $0.00000 | $0.00326 |
| Sonnet 5 | $0.00000 | $0.00130 |
| Haiku 4.5 | $0.00000 | $0.00065 |
Grade A, and why
codex 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 — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.
OpenAI Codex
Use OpenAI's Codex CLI with agentkernel for isolated code execution.
Integration Levels
| Level | How It Works | Setup |
|---|---|---|
| MCP Tools | Codex calls agentkernel MCP tools for sandbox control | agentkernel plugin install codex |
| Full Isolation | Run Codex itself inside an agentkernel sandbox | agentkernel sandbox create + agentkernel attach |
Codex has its own native sandbox using OS-level primitives (Seatbelt on macOS, Landlock + seccomp on Linux). That sandbox cannot be replaced with a custom runtime. The MCP plugin gives Codex access to agentkernel sandboxes as tools it can call.
Plugin Mode (Recommended)
Codex runs locally, code execution is sandboxed via MCP:
# Install the MCP config into your project
agentkernel plugin install codex
# This adds the agentkernel MCP server to .mcp.json
# Codex will have access to: run_command, create_sandbox, exec_in_sandbox, list_sandboxes, remove_sandbox
For global installation:
agentkernel plugin install codex --global
Sandbox Mode
Run Codex itself inside an isolated sandbox:
# Create sandbox with Codex pre-installed
agentkernel sandbox create codex-dev --config examples/agents/codex/agentkernel.toml
# Start the sandbox
agentkernel sandbox start codex-dev
# Run Codex with your API key
agentkernel attach codex-dev -e OPENAI_API_KEY=$OPENAI_API_KEY
# Inside the sandbox:
codex
API Key
Codex requires an OpenAI API key. Get one from platform.openai.com.
# Interactive session
agentkernel attach codex-dev -e OPENAI_API_KEY=$OPENAI_API_KEY
# One-off command
agentkernel exec codex-dev -e OPENAI_API_KEY=$OPENAI_API_KEY -- \
codex "Write a hello world function"
Configuration
The example config at examples/agents/codex/agentkernel.toml:
[sandbox]
name = "codex-sandbox"
[build]
dockerfile = "Dockerfile"
[agent]
preferred = "codex"
compatibility_mode = "codex"
[resources]
vcpus = 2
memory_mb = 1024
[security]
profile = "moderate"
network = true # Codex needs network for API calls
mount_cwd = true # Mount project directory
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 First seen · 100 lines · 0 tokens per session scan A 3eb88b6cd27b
codex is an agent published in the GitHub repository thrashr888/agentkernel (58 stars, last pushed 2d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 651 tokens. 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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