ctxlint

     

Lint your AI agent context files, MCP server configs, and session data against your actual codebase. Context linting + MCP config linting + session auditing. 16 AI tools, 8 MCP clients, cross-project consistency, auto-fix. Works as a CLI, CI step, pre-commit hook, or MCP server.

Your CLAUDE.md is lying to your agent. Your .mcp.json has a hardcoded API key. ctxlint catches both.


One click adds this to your local Yaw MCP config so it's available in every Yaw Terminal session. Or install manually below.

Why ctxlint?

Every AI coding tool ships a context file: CLAUDE.md, .cursorrules, AGENTS.md, .mcp.json. These files are the single most important interface between you and your agent — they tell it what to build, how to test, where things live.

But context files rot fast. You rename a file, change a build script, or switch from Jest to Vitest — and your CLAUDE.md still says the old thing. Your agent follows those stale instructions faithfully, then fails. You lose 10 minutes debugging what turns out to be a wrong path in line 12 of a markdown file.

Multiply that across a team with 5 context files, 3 MCP configs, and 2 people who touched the build system last week — and you have a real problem with no existing solution.

ctxlint is a linter purpose-built for this. It reads your context files, cross-references them against your actual codebase, and catches the drift before your agent does.

• Instant startup — ships as a single self-contained bundle with zero runtime dependencies. npx downloads a ~400 KB tarball and starts immediately
• Catches real problems — broken paths, wrong commands, stale references, contradictions across files
• Smart suggestions — detects git renames and fuzzy-matches to suggest the right path
• Auto-fix — --fix rewrites broken paths automatically using git history
• Token-aware — shows how much context window your files consume and flags redundant content
• Every AI tool — supports Claude Code, Cursor, Copilot, Windsurf, Gemini, Cline, Aider, and 9 more
• Multiple outputs — text, JSON, and SARIF (GitHub Code Scanning)
• MCP server — 7 tools for IDE/agent integration with tool annotations for auto-approval
• Watch mode — --watch re-lints automatically when context files change

Install

Run directly (no install needed):

npx -y @yawlabs/ctxlint@latest

Project install (recommended for teams)

npm install -D @yawlabs/ctxlint
# or
pnpm add -D @yawlabs/ctxlint

Then add to your package.json scripts:

{
  "scripts": {
    "lint:ctx": "ctxlint --strict"
  }
}

Global install

npm install -g @yawlabs/ctxlint

Useful if you want ctxlint available in every project without per-project setup.

What It Checks

| Check | What it finds | | --------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Broken paths | File references in context that don't exist in your project | | Wrong commands | Build/test commands that don't match your package.json scripts or Makefile targets | | Stale context | Context files not updated after recent code changes | | Token waste | How much context window your files consume per session | | Redundancy | Content the agent can already infer (e.g. "We use React" when react is in package.json) | | Contradictions | Conflicting directives across context files (e.g. "use Jest" in one, "use Vitest" in another) | | Frontmatter | Invalid or missing YAML frontmatter in Cursor .mdc, Copilot instructions, and Windsurf rules | | CI coverage | Release/deploy workflows in .github/workflows/ not documented in any context file | | CI secrets | Secrets used in CI workflows (${{ secrets.X }}) not mentioned in context files | | Inline secrets | Real secrets pasted into context files — private-key headers, AWS/GitHub/Anthropic/OpenAI/npm/Slack/Google/Stripe token shapes. Messages never echo the secret (6-char redacted prefix only) | | Dead hooks | PreToolUse hooks / permissions entries in .claude/settings.json pointing at scripts that no longer exist (a dead gate silently no-ops). Scans project .claude/settings.json[.local] by default; pass --hooks-global to also scan the user-global ~/.claude/settings.json | | Missing secrets | GitHub secrets set on sibling repos but missing from current project | | Diverged configs | Canonical config files (CI, tsconfig, etc.) drifting across sibling projects | | Missing workflows | GitHub Actions workflows present in 2+ siblings but absent here | | Stale memory | Claude Code memory entries referencing paths that no longer exist | | Duplicate memory | Near-duplicate memories across projects (>60% content overlap) | | Loop detection | Agent stuck in loops — repeated commands or cyclic patterns in session history | | Memory overflow | MEMORY.md past Claude Code's 200-line / 25KB session-load cap — entries beyond it are invisible to the agent |

Supported Context Files

| File | Tool | | ---------------------------------------------------------------------------------------------------- | --------------------------- | | CLAUDE.md, CLAUDE.local.md, .claude/rules/.md | Claude Code | | AGENTS.md, AGENT.md, AGENTS.override.md | AAIF / Multi-agent standard | | .cursorrules, .cursor/rules/.md, .cursor/rules/.mdc, .cursor/rules//RULE.md | Cursor | | .github/copilot-instructions.md, .github/instructions/.md, .github/git-commit-instructions.md | GitHub Copilot | | .windsurfrules, .windsurf/rules/.md | Windsurf | | GEMINI.md | Gemini CLI | | .clinerules | Cline | | .aiderules | Aider | | .aide/rules/.md | Aide / Codestory | | .amazonq/rules/.md | Amazon Q Developer | | .goose/instructions.md, .goosehints | Goose by Block | | .junie/guidelines.md, .junie/AGENTS.md | JetBrains Junie | | .aiassistant/rules/.md | JetBrains AI Assistant | | .continuerules, .continue/rules/.md | Continue | | .rules | Zed | | replit.md | Replit |

MCP Server Config Linting

ctxlint also lints MCP server configuration files — the JSON configs that tell AI clients which tools to connect to. These are context interfaces too: they shape what your agent can do.

# Lint context files + MCP configs
npx @yawlabs/ctxlint@latest --mcp

# Lint only MCP configs
npx @yawlabs/ctxlint@latest --mcp-only

# Include global/user-level configs (Claude Desktop, Cursor, Windsurf, etc.)
npx @yawlabs/ctxlint@latest --mcp-global

What MCP config files are scanned

| File | Client | | ----------------------------- | -------------------------------------- | | .mcp.json | Claude Code (universal project config) | | .cursor/mcp.json | Cursor | | .vscode/mcp.json | VS Code / GitHub Copilot | | .amazonq/mcp.json | Amazon Q Developer | | .continue/mcpServers/*.json | Continue |

With --mcp-global, also scans Claude Desktop, Cursor, Windsurf, and Amazon Q global configs.

What MCP config checks catch

| Check | What it finds | | --------------- | -------------------------------------------------------------------------------------- | | Schema | Invalid JSON, wrong root key (servers vs mcpServers), missing required fields | | Security | Hardcoded API keys and Bearer tokens in git-tracked config files | | Commands | Missing cmd /c wrapper for npx on Windows, broken file paths in args | | Deprecated | SSE transport usage (deprecated March 2025, use Streamable HTTP) | | Env vars | Wrong env var syntax for the client (${VAR} vs ${env:VAR} vs ${{ secrets.VAR }}) | | URLs | Malformed URLs, localhost in project configs, missing path component | | Consistency | Same server configured differently across client configs | | Redundancy | Disabled servers, identical configs at multiple scopes |

Example MCP config output

MCP Configs
  .mcp.json
    ✗ mcp-security    Server "api": hardcoded Bearer token in a git-tracked file
    ✗ mcp-deprecated  Server "old-svc": SSE transport is deprecated — use "http"
    ✓ mcp-schema
    ✓ mcp-commands
  .cursor/mcp.json
    ✗ mcp-env  Server "api": Cursor uses ${env:VAR}, not ${VAR}
    ✓ mcp-schema
  .vscode/mcp.json
    ✗ mcp-schema  .vscode/mcp.json must use "servers" as root key, not "mcpServers"

Cross-file
    ⚠ Server "api" is configured differently in .mcp.json and .cursor/mcp.json
    ℹ Server "db" is in .mcp.json but missing from .cursor/mcp.json

Summary: 3 errors, 2 warnings, 1 info

MCP Config Linting Specification

The full specification for MCP config linting rules, the cross-client config landscape, and a machine-readable rule catalog are published as open specifications:

• MCP_CONFIG_LINT_SPEC.md — the full lint-rule set (rule count in the Specifications family table), the complete client/format reference, and implementation guidance. Tool-agnostic — any linter can implement it.
• mcp-config-lint-rules.json — Machine-readable rule catalog for programmatic consumption by AI agents, CI systems, and other tools.

Session Linting

ctxlint can audit AI agent session data — history files and memory entries — for cross-project consistency. Session checks compare your current project against sibling repos to catch drift and missing setup.

# Lint context files + session data
npx @yawlabs/ctxlint@latest --session

# Lint only session data
npx @yawlabs/ctxlint@latest --session-only

Session checks are opt-in because they access files outside the project directory (agent history in your home directory, sibling repos in the parent directory).

What session files are scanned

| Agent | History | Memory | | ----------- | ------------------------- | ---------------------------------- | | Claude Code | ~/.claude/history.jsonl | ~/.claude/projects//memory/.md | | Codex CLI | ~/.codex/history.jsonl | — |

What session checks catch

| Check | What it finds | | ------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ | | Missing secrets | gh secret set ran on 2+ sibling repos but not this one | | Diverged configs | Shared config files (CI workflows, tsconfig, .prettierrc, etc.) with 20-90% line overlap — enough to be related, different enough to be drifting | | Missing workflows | GitHub Actions workflows in 2+ siblings but absent from this project | | Stale memory | Memory entries referencing file paths that no longer exist | | Duplicate memory | Near-duplicate memory entries across projects (>60% overlap) | | Loop detection | Agent stuck in a loop — 3+ consecutive identical commands, or cyclic A,B,A,B patterns | | Memory index overflow | MEMORY.md exceeds Claude Code's documented 200-line / 25KB session-load cap, so entries past the cap are invisible to the agent |

Session Linting Specification

• AGENT_SESSION_LINT_SPEC.md — the full lint-rule set (rule count in the Specifications family table), the agent session data landscape across 8 agents, sibling detection strategy, and implementation guidance.
• agent-session-lint-rules.json — Machine-readable rule catalog.

Example Output

ctxlint v0.9.10

Scanning /Users/you/my-app...

Found 2 context files (1,847 tokens total)
  CLAUDE.md (1,203 tokens, 42 lines)
  AGENTS.md -> CLAUDE.md (symlink)

CLAUDE.md
  ✗ Line 12: src/auth/middleware.ts does not exist
    → Did you mean src/middleware/auth.ts? (renamed 14 days ago)
  ✗ Line 8: "pnpm test" — script "test" not found in package.json
  ⚠ Last updated 47 days ago. src/routes/ has 8 commits since.
  ⚠ testing framework conflict: "Vitest" in CLAUDE.md vs "Jest" in AGENTS.md
  ℹ Line 3: "Express" is in package.json dependencies — agent can infer this

Summary: 2 errors, 2 warnings, 1 info
  Token usage: 1,203 tokens per agent session
  Estimated waste: ~55 tokens (redundant content)

Options

Usage: ctxlint [options] [path]

Arguments:
  path                 Project directory to scan (default: ".")

Options:
  --strict                  Exit code 1 on any warning or error (for CI)
  --checks <list>           Comma-separated checks to run (see below)
  --ignore <list>           Comma-separated checks to skip
  --fix                     Auto-fix broken paths using git history and fuzzy matching
  --fix-dry-run             Preview --fix changes without writing
  --yes                     Skip interactive confirmation prompts (required for --fix in TTY)
  --follow-symlinks         Allow --fix to write through symlinks (default: skip)
  --format <fmt>            Output format: text, json, or sarif (default: text)
  --tokens                  Show token breakdown per file
  --verbose                 Show passing checks too
  --quiet                   Suppress all output except errors (exit code only)
  --config <path>           Path to config file (default: .ctxlintrc in project root)
  --depth <n>               Max subdirectory depth to scan (default: 2)
  --mcp                     Enable MCP config linting alongside context file checks
  --mcp-only                Run only MCP config checks, skip context file checks
  --mcp-global              Also scan user/global MCP config files (implies --mcp)
  --session                 Enable session audit checks (cross-project consistency)
  --session-only            Run only session checks, skip context and MCP checks
  --skills                  Run agent-skill checks (~/.claude/skills + ~/.claude/agents)
  --skills-only             Run only agent-skill checks, skip everything else
  --hooks-global            Also scan the user-global ~/.claude/settings.json in the
                            dead-hook check (default scans project .claude/ only)
  --mcp-server              Start the MCP server (alias: `serve` subcommand)
  --watch                   Re-lint on context file changes
  -V, --version             Output the version number
  -h, --help                Display help

Commands:
  init                 Set up a git pre-commit hook

Available checks: paths, commands, staleness, tokens, tier-tokens, redundancy, contradictions, frontmatter, ci-coverage, ci-secrets, content-secrets, hook-coverage, mcp-schema, mcp-security, mcp-commands, mcp-deprecated, mcp-env, mcp-urls, mcp-consistency, mcp-redundancy, session-missing-secret, session-diverged-file, session-missing-workflow, session-stale-memory, session-duplicate-memory, session-loop-detection, session-memory-index-overflow, skill-frontmatter, skill-broken-ref, skill-trigger-collision, skill-orphaned, skill-dead-tool-restriction

Passing any mcp- check name implies --mcp. Passing any session- check name implies --session. Passing any skill-* check name implies --skills.

Watch Mode

npx @yawlabs/ctxlint@latest --watch

Re-lints automatically when any context file, MCP config, or package.json changes. Useful during development when you're editing context files alongside code.

Use in CI

- name: Lint context files
  run: npx @yawlabs/ctxlint@latest --strict

Exit Codes

| Code | Meaning | | ---- | -------------------------------------------------------------------- | | 0 | Success — no issues, or issues below the strict threshold | | 1 | Strict mode caught at least one error or warning (--strict is set) | | 2 | Config error, invalid CLI option, or internal failure |

In non-strict mode ctxlint always exits 0 — it's a reporting tool by default. Pass --strict to enforce in CI.

GitHub Action

- name: Lint context files
  uses: yawlabs/ctxlint-action@v1

Or with options:

- name: Lint context files
  uses: yawlabs/ctxlint-action@v1
  with:
    args: '--strict --mcp'

SARIF Output (GitHub Code Scanning)

- name: Lint context files
  run: npx @yawlabs/ctxlint@latest --format sarif > ctxlint.sarif

- name: Upload SARIF
  uses: github/codeql-action/upload-sarif@v3
  with:
    sarif_file: ctxlint.sarif

Auto-fix

npx @yawlabs/ctxlint@latest --fix

When a broken path was renamed in git or has a close match in the project, --fix rewrites the context file automatically.

Pre-commit Hook

Built-in

npx @yawlabs/ctxlint@latest init

Sets up a git pre-commit hook that runs ctxlint --strict before each commit.

pre-commit framework

Add to your .pre-commit-config.yaml:

repos:
  - repo: https://github.com/yawlabs/ctxlint
    rev: v0.9.10
    hooks:
      - id: ctxlint

Config File

Create a .ctxlintrc or .ctxlintrc.json in your project root:

{
  "checks": ["paths", "commands", "tokens", "contradictions", "frontmatter"],
  "ignore": ["redundancy"],
  "strict": true,
  "tokenThresholds": {
    "info": 500,
    "warning": 2000,
    "error": 5000,
    "aggregate": 4000,
    "tierBreakdown": 1000,
    "tierAggregate": 4000
  },
  "contextFiles": ["CONVENTIONS.md", "docs/ai-rules.md"]
}

The contextFiles array adds custom file patterns to scan alongside the built-in list. Useful for project-specific context files like CONVENTIONS.md.

Config Reference

| Field | Type | Default | Meaning | | ------------------------------- | ---------- | ---------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | checks | string[] | all checks | Checks to run. Check names include paths, commands, tokens, tier-tokens, redundancy, contradictions, frontmatter, staleness, ci-coverage, ci-secrets, content-secrets, hook-coverage, plus any mcp- / session- / skill-*. | | ignore | string[] | [] | Checks to skip, evaluated after checks. | | strict | boolean | false | Exit non-zero on any warning or error. | | tokenThresholds | object | see below | Per-file and cross-file token thresholds. | | tokenThresholds.info | number | 1000 | Per-file info threshold for tokens/info. | | tokenThresholds.warning | number | 3000 | Per-file warning threshold for tokens/large. | | tokenThresholds.error | number | 8000 | Per-file error threshold for tokens/excessive. | | tokenThresholds.aggregate | number | 5000 | Cross-file total threshold for tokens/aggregate. | | tokenThresholds.tierBreakdown | number | 1000 | Always-loaded file threshold for tier-tokens/section-breakdown. | | tokenThresholds.tierAggregate | number | 4000 | Combined always-loaded threshold for tier-tokens/aggregate. | | contextFiles | string[] | [] | Extra glob patterns to scan alongside the built-in list. | | mcp | boolean | false | Enable MCP config checks by default (same as --mcp). | | mcpOnly | boolean | false | Run only MCP config checks, skip context-file checks (same as --mcp-only). | | mcpGlobal | boolean | false | Also scan user/global MCP configs (same as --mcp-global). | | session | boolean | false | Enable session audit checks (cross-project consistency); same as --session. | | sessionOnly | boolean | false | Run only session checks, skip context and MCP checks (same as --session-only). | | skills | boolean | false | Enable agent-skill checks (~/.claude/skills + ~/.claude/agents); same as --skills. | | skillsOnly | boolean | false | Run only agent-skill checks, skip everything else (same as --skills-only). |

Config file resolution order: .ctxlintrc → .ctxlintrc.json in the project root. Use --config <path> to point elsewhere. CLI flags override config fields.

CLI flags override config file settings. Use --config <path> to load a config from a custom location.

Use as MCP Server

ctxlint ships with an MCP server that exposes seven tools (ctxlint_audit, ctxlint_mcp_audit, ctxlint_session_audit, ctxlint_skill_audit, ctxlint_validate_path, ctxlint_token_report, ctxlint_fix). All read-only tools declare annotations so MCP clients can skip confirmation dialogs.

Launch it with the serve subcommand (or the equivalent --mcp-server flag, kept for back-compat):

npx -y @yawlabs/ctxlint@latest serve

With Claude Code

claude mcp add ctxlint -- npx -y @yawlabs/ctxlint@latest serve

With .mcp.json (Claude Code project config, Cursor, Windsurf)

Create .mcp.json in your project root:

macOS / Linux / WSL:

{
  "mcpServers": {
    "ctxlint": {
      "command": "npx",
      "args": ["-y", "@yawlabs/ctxlint@latest", "serve"]
    }
  }
}

Windows:

{
  "mcpServers": {
    "ctxlint": {
      "command": "cmd",
      "args": ["/c", "npx", "-y", "@yawlabs/ctxlint@latest", "serve"]
    }
  }
}

Tip: This file is safe to commit — it contains no secrets.

With VS Code / GitHub Copilot

Add to .vscode/mcp.json:

{
  "servers": {
    "ctxlint": {
      "command": "npx",
      "args": ["-y", "@yawlabs/ctxlint@latest", "serve"]
    }
  }
}

With Claude Desktop

Add to your Claude Desktop config (claude_desktop_config.json):

{
  "mcpServers": {
    "ctxlint": {
      "command": "npx",
      "args": ["-y", "@yawlabs/ctxlint@latest", "serve"]
    }
  }
}

JSON Output

npx @yawlabs/ctxlint@latest --format json

Returns structured JSON with all file results, issues, and summary — useful for building integrations or dashboards.

Specifications

ctxlint is the reference implementation of four open specifications for linting AI agent interfaces. These specs are tool-agnostic — any linter, IDE extension, or CI system can implement them.

| Spec | What it covers | | -------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | AI Context File Linting Spec | 39 rules for validating context files (CLAUDE.md, .cursorrules, AGENTS.md, etc.) across 16 clients. Covers file formats, frontmatter schemas, path/command validation, staleness, token budgets, redundancy, and contradictions. | | MCP Config Linting Spec | 29 rules for validating MCP server configs (.mcp.json, .cursor/mcp.json, .vscode/mcp.json, etc.) across 8 clients. Covers schema validation, hardcoded secrets, env var syntax, deprecated transports, and cross-file consistency. | | Agent Session Linting Spec | 8 rules for auditing agent session data (history, memory) across 8 agents. Covers cross-project secret consistency, config drift, stale memory, and loop detection. | | Agent Skill Linting Spec | 5 rules for auditing Claude Code skill (SKILL.md) and agent (.md) definitions under ~/.claude. Covers frontmatter presence, broken refs, trigger-phrase collisions, orphaned skills, and dead tool restrictions. (v1, experimental) |

All specs include machine-readable rule catalogs for programmatic consumption:

• context-lint-rules.json — context file rules and 16 supported format definitions
• mcp-config-lint-rules.json — MCP config rules and 8 client definitions
• agent-session-lint-rules.json — session lint rules and 8 agent data source definitions
• agent-skill-lint-rules.json — agent-skill lint rules (~/.claude/skills, ~/.claude/agents)

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License

MIT