Show HN: CtxWise – Stop 8MB MCP crashes, schema bloat, and cache misses

Stop burning 30,000+ startup tokens on bloated MCP tool schemas, diverging CLAUDE.md / AGENTS.md files, and hidden prompt leaks.

The local-first AI Context Firewall, MCP Schema Tree-Shaker, and Token Profiler for Claude Code, OpenAI Codex, and Cursor.

⚡ 30s Quickstart · 📊 Before vs. After · 🌳 MCP Tree-Shaker · 🛡️ Security Shield · 🤖 GitHub Action · 🤝 5-Min PRs

💡 Using Claude Code, OpenAI Codex, or Cursor? Drop a ⭐ Star on GitHub so you can find CtxWise whenever your MCP servers or CLAUDE.md / AGENTS.md files start bloating your context window!

Zero config, zero API keys, zero model calls. Run directly with npx in any repository:

npx @framy2/ctxwise mcp-xray --probe-stdio

npx @framy2/ctxwise agents

npx @framy2/ctxwise shield --fail-on-risk

npx @framy2/ctxwise sync --compress --cursor

Modern coding agents (Claude Code, OpenAI Codex CLI, Cursor) load CLAUDE.md, AGENTS.md, .cursor/rules, skill catalogs, and every connected MCP server's JSON schema on every turn:

flowchart LR
    subgraph Sources["Active Agent Context Surface"]
        C["Claude Code\nCLAUDE.md · .mcp.json · .claude/skills"]
        O["OpenAI Codex\nAGENTS.md · config.toml · .codex/skills"]
        U["Cursor\n.cursorrules · .cursor/rules/*.mdc"]
    end

    subgraph Engine["CtxWise Local Engine (0 API Calls · <50ms)"]
        A["ctxwise agents & sync\nCross-Agent Parity + Token Diet"]
        M["ctxwise mcp-xray\nMCP Tool Schema Tree-Shaker"]
        S["ctxwise shield\nSecret & Prompt-Injection Firewall"]
        B["ctxwise budget & drift\nDeterministic Lock & CI Gate"]
    end

    Sources --> Engine
    Engine --> Out1["Lean, Synced Context\n(-29% to -73% Token Overhead)"]
    Engine --> Out2["GitHub Action CI Gate\nuses: FramY2/ctxwise@v1"]

Discover all MCP servers declared across .mcp.json, .cursor/mcp.json, .vscode/mcp.json (VS Code's top-level "servers" key), ~/.claude.json, and ~/.codex/config.toml. Measure exact token weights per tool schema (from a saved tools/list JSON file or by probing local stdio servers live) and spot [BLOATED] tools (>= 250 tokens or >= 12 input properties):

npx @framy2/ctxwise mcp-xray --probe-stdio
CtxWise mcp-xray · 3 MCP servers declared · 18 tool schemas analyzed · ~6,420 schema tokens (estimated)

Heaviest MCP tool schemas:
- ~890 tokens · github/create_or_update_pull_request (16 params, 3,560 chars) [BLOATED]
- ~640 tokens · postgres/execute_migration_plan (14 params, 2,560 chars) [BLOATED]

Tree-shaking potential: ~1,530 tokens/turn savable by pruning bloated tools.

Keep Claude Code (CLAUDE.md, .claude/rules/, .claude/skills, .claude/commands, .mcp.json), OpenAI Codex ( AGENTS.md, .codex/skills), and Cursor (.cursor/rules/*.mdc) 100% aligned while stripping markdown bloat (HTML comments, duplicate bullet rules, blank padding) without touching fenced code blocks. In CI, ctxwise agents --fail-on-divergence exits 1 when CLAUDE.md and AGENTS.md drift apart:

npx @framy2/ctxwise agents
npx @framy2/ctxwise agents --fail-on-divergence
npx @framy2/ctxwise sync --compress --cursor

Protect your repository before an agent reads your workspace or before a PR merges:

• Secret Exposure Detection: Catches hardcoded Anthropic (sk-ant-... ), OpenAI (sk-proj-... ), GitHub (ghp_... ), AWS (AKIA... ), and private key blocks insideCLAUDE.md ,AGENTS.md ,.mcp.json , and skills.
• Prompt Injection & Trojan Unicode Guard: Detects override directives (ignore all previous instructions ), covert HTML comment payloads (<!-- curl ... --> ), and hidden bidirectional/zero-width Unicode characters.
• Claude Settings Hygiene & SARIF 2.1.0 Output: Flags misplaced"mcpServers" blocks inside.claude/settings.json (anthropics/claude-code#105885 ) and emits SARIF 2.1.0 (--sarif ctxwise.sarif ) for GitHub Code Scanning.
• Unpinned MCP Launchers (unpinned-mcp-exec): Flags MCP servers that run an unpinned or@latest package throughnpx /uvx style launchers, so a compromised upstream release cannot silently enter your agent's tool surface.

npx @framy2/ctxwise shield --fail-on-risk --sarif ctxwise.sarif

Bootstrap a reviewable token budget (ctxwise.budget.yaml) and lean starter AGENTS.md + CLAUDE.md files tailored to your stack in one command:

npx @framy2/ctxwise preset
npx @framy2/ctxwise preset nextjs-typescript --with-guidance
npx @framy2/ctxwise budget --fail-on-exceed   # auto-loads ./ctxwise.budget.yaml

ctxwise budget covers Claude Code, Codex, and Cursor startup files. By default (--agent all) the limit applies to the heaviest single agent session, so a synced CLAUDE.md + AGENTS.md pair is never double-counted; use --agent codex|claude|cursor to budget one agent.

Built-in presets include:

• nextjs-typescript (Next.js + TypeScript + Tailwind)
• sveltekit /sveltekit-typescript (SvelteKit 2 + Svelte 5 Runes + TypeScript)
• python-fastapi (Python 3.12 + FastAPI + Pydantic v2)
• rust-cargo (Rust + Cargo Workspace)
• go-microservice (Go 1.23+ Service)
• mcp-server-dev (Model Context Protocol Server)
• monorepo-turbo (Turborepo / pnpm Monorepo)

Add CtxWise to .github/workflows/ci.yml in 5 lines to automatically block secret leaks, prompt injection, and context token bloat on every Pull Request:

- name: AI Context Firewall & Token Budget Guard
  uses: FramY2/ctxwise@v1
  with:
    max-known-tokens: "4000"
    fail-on-secrets: "true"
    check-agent-parity: "true"
    sarif-file: "ctxwise-shield.sarif"

When ./ctxwise.budget.yaml exists (or budget-policy points at a policy file), the Action uses it instead of max-known-tokens. check-agent-parity: "true" runs ctxwise agents --fail-on-divergence, and every run appends a Markdown report (shield status, per-agent token breakdown, budget status) to the job summary.

CtxWise ships a native Claude Code plugin manifest (.claude-plugin/plugin.json + .claude-plugin/marketplace.json) that installs the ctxwise skill:

/plugin marketplace add FramY2/ctxwise
/plugin install ctxwise@ctxwise

• FramY2/mcp-diet (@framy2/mcp-diet) : Zero-dependency stdio MCP proxy & runtime firewall — deterministictools/list tree-shaking (--allow ,--deny ,--read-only ,--max-desc ), oversizedtools/call crash guard (--max-result-kb foranthropics/claude-code#105703 ), and live credential redaction (--redact-secrets ).
• FramY2/agent-wire-tap (@framy2/agent-wire-tap) : Zero-cost local loopback HTTP interceptor & CI contract tester for coding agents (codex ,claude ) — captures exact outbound wire payloads and verifies system prompt, tool count, and byte budget contracts with**$0.00 API cost** .
• Interactive Context & MCP Token Tax Calculator : 100% client-side web app to measure per-turn MCP schema tax, 50-turn session cost across Claude Opus 4.7 / Opus 5.5 / Sonnet 5.5 / GPT-6.1-Sol / GPT-6-Luna (2026-11-11 list prices), Codex32 KiB truncation status, and leaked secrets. Accepts.mcp.json and.vscode/mcp.json .
• ctxwise-vscode (editors/vscode) : Lightweight VS Code & Cursor status-bar extension displaying live workspace token tax, Context Grade (A –F ), Codex32 KiB cap percentage, and secret alerts.

The public microbenchmark ran 10 paired tasks across requested GPT-5.6 Luna, Terra, and Sol profiles: 20/20 answers passed the same exact validator. Removing irrelevant discovered context reduced the estimated model-visible prompt by 73.3% and exact aggregate turn tokens by 29.1% (with a second maintainer repeat measuring 28.5% across nine comparable pairs).

Read the method and limitations or inspect the machine-readable summary.

New to profiles? Follow the lean-profile walkthrough: it turns a real audit finding into a reviewable lean profile, end to end.

Want to make your first open-source contribution to an AI developer tool? Adding a new stack preset in presets/ takes less than 5 minutes (just 1 YAML file, validated automatically by npm test):

• 🟢 Issue #23 — Addsveltekit-typescript preset (SvelteKit 2 + Svelte 5 Runes)
• 🟢 Issue #24 — Addastro-content preset (Astro 5 + Content Layer)
• 🟢 Issue #25 — Adddjango-ninja preset (Python + Django 5 + Django Ninja)
• 🟢 Issue #26 — Addlaravel-inertia preset (Laravel 11 + Inertia.js + PHP 8.3)
• 🟢 Issue #27 — Addkotlin-spring-boot preset (Kotlin + Spring Boot 3)
• 🟢 Issue #28 — Addcloudflare-workers-hono preset (Cloudflare Workers + Hono)

See CONTRIBUTING.md for the 3-step guide!

See Architecture, Cost semantics, and Privacy and security.

Apache-2.0. See LICENSE and NOTICE.

If CtxWise saved you tokens or caught a bloated MCP schema, please give the repo a ⭐ Star on GitHub!

⭐ Star FramY2/ctxwise on GitHub