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 mcp.hosting account so it syncs to every MCP client you use. Or install manually below.

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

Run directly (no install needed):

npx @yawlabs/ctxlint

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

Then add to your package.json scripts:

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

npm install -g @yawlabs/ctxlint

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

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 --mcp

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

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

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

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

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 — 43 lint rules across 8 categories, 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.

ctxlint also lints .mcph.json — the config file read by the @yawlabs/mcph CLI, which orchestrates MCP servers via the mcp.hosting registry. Distinct from .mcp.json (different schema, different threat model). Applies across the user-global (~/.mcph.json), per-project (.mcph.json), and machine-local (.mcph.local.json) scope cascade.

# Lint context files + .mcph.json
npx @yawlabs/ctxlint --mcph

# Lint only .mcph.json
npx @yawlabs/ctxlint --mcph-only

# Include the user-global ~/.mcph.json
npx @yawlabs/ctxlint --mcph-global

# Treat any token in any .mcph.json as an error (env-var-only posture)
npx @yawlabs/ctxlint --mcph --mcph-strict-env-token

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 --session

# Lint only session data
npx @yawlabs/ctxlint --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).

• AGENT_SESSION_LINT_SPEC.md — 8 lint rules, the agent session data landscape across 8 agents, sibling detection strategy, and implementation guidance.
• agent-session-lint-rules.json — Machine-readable rule catalog.

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)

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)
  --mcph                    Enable .mcph.json (mcp.hosting CLI config) linting
  --mcph-only               Run only mcph config checks
  --mcph-global             Also scan ~/.mcph.json (implies --mcph)
  --mcph-strict-env-token   Upgrade mcph-config/prefer-env-token from warning to error
  --session                 Enable session audit checks (cross-project consistency)
  --session-only            Run only session checks, skip context and MCP checks
  --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, mcp-schema, mcp-security, mcp-commands, mcp-deprecated, mcp-env, mcp-urls, mcp-consistency, mcp-redundancy, mcph-token-security, mcph-apibase, mcph-schema-conformance, mcph-lists, mcph-gitignore, session-missing-secret, session-diverged-file, session-missing-workflow, session-stale-memory, session-duplicate-memory, session-loop-detection, session-memory-index-overflow

Passing any mcp-* check name implies --mcp. Passing any mcph-* check name implies --mcph. Passing any session-* check name implies --session.

npx @yawlabs/ctxlint --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.

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

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

- 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'

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

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

npx @yawlabs/ctxlint --fix

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

npx @yawlabs/ctxlint init

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

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

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

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 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.

ctxlint ships with an MCP server that exposes seven tools (ctxlint_audit, ctxlint_mcp_audit, ctxlint_mcph_audit, ctxlint_session_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 serve

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

Create .mcp.json in your project root:

macOS / Linux / WSL:

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

Windows:

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

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

Add to .vscode/mcp.json:

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

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

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

npx @yawlabs/ctxlint --format json

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

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

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
• mcph-config-lint-rules.json — mcph CLI config rules (.mcph.json)
• agent-session-lint-rules.json — session lint rules and 8 agent data source definitions

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