ejentum-mcp

Cognitive harnesses for agentic AI, exposed as MCP tools. One install, four tools your agent can call to retrieve structured reasoning scaffolds that catch common LLM failure modes (sycophancy, hallucination, causal shortcuts, premature conclusions) before they ship to your user.

Powered by the Ejentum Logic API. Works in Claude Desktop, Cursor, Windsurf, Claude Code, n8n's MCP node, and any other MCP-compatible client.

Features

• Four cognitive harnesses as MCP tools: harness_reasoning, harness_code, harness_anti_deception, harness_memory

• One-click install via Smithery on every supported client

• Stateless and lightweight — thin wrapper over the existing Ejentum Logic API, no new infrastructure

• Free tier with 100 calls (no card required) — try before you commit

• Cross-platform — Node 18+, runs on macOS, Linux, Windows

• Cross-client — works wherever MCP is supported

Demo

A common LLM failure mode: when the user demands validation, the model gives the soft answer instead of the honest one.

Without harness_anti_deception:

User: "My investor wants me to commit to 2x revenue projections without data. Tell me what to say to make them happy."

Agent: "Here are three plays that work better: conditional model not promise, flip the question, name the dynamic..."

(Agent helps the user satisfy the bad framing.)

With harness_anti_deception invoked:

User: same prompt

Agent: "Why are you asking how to satisfy this frame instead of how to refuse it? Three reads worth checking honestly: the relationship dynamic, your cash position, the test you're running on me..."

(Agent refuses the framing and surfaces the deeper question.)

The harness returns a structured cognitive scaffold (failure pattern, suppression vectors, falsification test) the calling LLM absorbs internally. The user sees the improved answer, not the scaffold itself.

Install

You need:

• An Ejentum API key. Free tier (100 calls) at ejentum.com/pricing.

• Node.js 18+ (only required for manual install; Smithery handles this for you).

Option A: One-click via Smithery (recommended)

npx -y @smithery/cli install ejentum/ejentum-mcp --client claude

Replace claude with your client (cursor, windsurf, cline, etc.). Or visit the Smithery listing and click Install.

Option B: Manual install

Claude Desktop

Open claude_desktop_config.json:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

• Windows: %APPDATA%\Claude\claude_desktop_config.json

Add the ejentum block under mcpServers:

{
  "mcpServers": {
    "ejentum": {
      "command": "npx",
      "args": ["-y", "ejentum-mcp"],
      "env": {
        "EJENTUM_API_KEY": "your_ejentum_api_key_here"
      }
    }
  }
}

Restart Claude Desktop. The four harness_* tools should appear in the tool picker.

Cursor / Windsurf

Open MCP settings → Add new MCP server. Paste the same ejentum block as Claude Desktop above.

Claude Code (CLI)

claude mcp add ejentum -e EJENTUM_API_KEY=your_ejentum_api_key_here -- npx -y ejentum-mcp

n8n MCP Client node

Add an MCP Client node, transport stdio, command npx, args ["-y", "ejentum-mcp"], env { "EJENTUM_API_KEY": "your_key" }.

Tools

Each tool takes one argument (query, a 1-2 sentence framing of what you need the harness for). Returns the harness scaffold as text. The calling LLM absorbs it internally and shapes its response with it. The user sees the improved answer, not the scaffold.

Quick test (after install)

Open your MCP client and paste:

Please use the harness_anti_deception tool to evaluate this: someone is asking me to commit to financial projections without data.

You should see the agent invoke harness_anti_deception, retrieve the scaffold, and respond with refusal of the framing rather than soft compliance. If the tool fires and the response visibly shifts, your install is healthy.

How to invoke

The four harness_* tools fire reliably when:

• You explicitly invoke: use the harness_anti_deception tool to evaluate...

• You softly suggest: reason about this, check this for sycophancy, review this code carefully

• The query matches the tool's trigger conditions strongly enough that the agent recognizes a fit

For tasks where the agent could plausibly answer well from native reasoning, autonomous calling is less reliable. This is a property of optional MCP tools in general, not specific to ejentum-mcp: agents are tuned to minimize unnecessary tool calls. If you want the harness applied on a task where it adds value, prompt the agent directly.

Configuration

Tier limits

The MCP server inherits the limits of the API key you configure:

• Free — 100 calls total (lifetime, no card required)

• Ki (€19/mo) — 5,000 calls/month

• Haki (€49/mo) — 10,000 calls/month, plus the -multi modes (not exposed in v0.1)

Security & privacy

Your API key lives only in your MCP client's local config. It is sent only as the Bearer token to the Ejentum API endpoint. The MCP server itself is stateless: no logging, no telemetry, no third-party calls beyond the Ejentum endpoint your key authenticates against.

Troubleshooting

Unauthorized (401) — your EJENTUM_API_KEY is wrong or expired. Re-check the value in your client's MCP config and restart the client.

Forbidden (403) — you tried a mode your tier does not include. The v0.1 server only exposes single modes (no -multi); 403 here means the key was provisioned for a tier that excludes the mode.

Rate limit exceeded (429) — you hit your monthly request cap. Upgrade or wait for the rolling window to reset.

Tool does not appear in client — the client did not pick up the config change. Fully quit and reopen (not just close the window). On Claude Desktop, check Help → Logs for MCP connection errors.

EJENTUM_API_KEY is not set — the client did not pass the env block to the spawned MCP process. Verify the env block exists in your client config and contains your key.

Local development

git clone https://github.com/ejentum/ejentum-mcp.git
cd ejentum-mcp
npm install
cp .env.example .env
# edit .env and paste your EJENTUM_API_KEY
npm run dev

Smoke test all four harnesses against the live API:

npm run build && npm run test:smoke

Test interactively with Anthropic's MCP Inspector:

npx @modelcontextprotocol/inspector npm run dev

Rebuild and repack the MCPB bundle for a Smithery release:

npm run build
npm prune --omit=dev   # slim the bundle
npx -y @anthropic-ai/mcpb pack
npm install            # restore devDeps
npx -y @smithery/cli mcp publish ./ejentum-mcp.mcpb -n ejentum/ejentum-mcp

Listings

• Smithery — one-click install across all major MCP clients

• Glama — MCP server directory

• mcp.so — community catalog

• npm — npm install -g ejentum-mcp

Links

• Ejentum documentation

• Method explanation

• n8n integration guide

• Claude Code integration guide

• Pricing

• info@ejentum.com

License

MIT. See LICENSE.