Simple English hooks

The Claude Code and Codex plugins include a SessionStart hook. The hook loads the Simple English writing rules when a session starts, resumes, clears, or compacts. You do not need to name the skill.

The hook needs Node.js. Both plugins run src/hooks/simple-english-activate.js with the node command.

Install

Claude Code:

claude plugin marketplace add AminBlg/SimpleEnglish
claude plugin install simple-english@simple-english

Codex:

codex plugin marketplace add AminBlg/SimpleEnglish
codex plugin add simple-english@simple-english

Codex asks you to review and trust the hook before its first run. Open /hooks to approve it.

What the hook sends

The hook writes the fenced rule block of prompts/system-prompt.md to standard output, about 3,500 characters. The page title, the paste instructions, and the word-budget variant stay out. The full skill, skills/simple-english/SKILL.md, is about 7,500 characters, and Claude Code caps hook output at 10,000 characters. Output over the cap goes to a file and the model gets only a preview. The condensed rules fit, and the hook names the full skill path so the model can read it for a compliance check or strict mode.

Codex applies its own cap to hook context. The additionalContextLimit: 0 setting in .codex-plugin/hooks.json turns off the spill-to-disk threshold. It does not remove the cap. The condensed rules fit under it.

If the hook cannot read the prompt file, it tries the next location. If every location fails, it prints a short fallback rule set and exits 0. The session still starts.

Where each harness loads the hook

• Claude Code: the hooks field in .claude-plugin/plugin.json.
• Codex: .codex-plugin/hooks.json, named by the hooks field in .codex-plugin/plugin.json. The marketplace catalog is .agents/plugins/marketplace.json.

Test

From the repository root:

node --test src/hooks/simple-english-activate.test.js

Advisory writing checks (Claude Code)

Two more hooks run under Claude Code, both advisory. Neither one blocks.

• PostToolUse on Write and Edit: when the file is Markdown, src/hooks/lint_hook.py lints it with evals/ste_lint.py and shows a one-line summary of the violations to the model.
• Stop: the same script reads the last reply and adds a system message when the reply breaks the register: an em-dash, bold, a header, a list item, a filler opener or closer, or a slop word.

Codex runs only the SessionStart hook. Test the checks with python3 src/hooks/test_lint_hook.py.

What the file check skips

The writing rules cover the documents that you write for a reader. They do not cover the files that the agent keeps for itself, such as memory files. A summary of the violations in such a file only spends tokens. The PostToolUse check therefore skips three groups of paths:

• Every path under the Claude configuration directory. The check reads CLAUDE_CONFIG_DIR and falls back to ~/.claude.
• Every path with a .claude directory component, for example my-project/.claude/agent-memory/reviewer/MEMORY.md. A skill or a command that you write under .claude/ is also skipped.
• Every path that matches a glob in SIMPLE_ENGLISH_LINT_EXCLUDE.

A symlink does not defeat a skip. The check tests the absolute path in two forms, as written and with the symlinks resolved. A match on either form is enough.

SIMPLE_ENGLISH_LINT_EXCLUDE holds glob patterns, separated by the path separator of the platform (: on Linux and macOS, ; on Windows). In a pattern, * also matches /. The check expands a leading ~ to your home directory.

export SIMPLE_ENGLISH_LINT_EXCLUDE="$HOME/notes/*:*/CHANGELOG.md"

To turn the file check off, set the variable to *. The Stop reply check stays on.