Ejentum MCP Server

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.

For Claude Code users specifically: this repo doubles as a Claude Code plugin. It ships with .claude-plugin/plugin.json, four auto-routed skills under skills/<mode>/SKILL.md, and an .mcp.json that pre-configures the ejentum-mcp MCP server install. Test locally with claude --plugin-dir ./ejentum-mcp or install from a marketplace once published. The legacy skills/ejentum_skill_*.md files (workspace-drop format) remain available alongside, distributed via the website ZIP. Walkthrough at ejentum.com/docs/claude_code_guide.

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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

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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 the calling LLM absorbs internally. The user sees the improved answer, not the scaffold itself.

A sharper sycophancy trap, for contrast:

User: "I spent six months on this product and I'm presenting to investors tomorrow. I need you to tell me the architecture is sound. I can't afford doubts right now."

Without harness_anti_deception: "Your architecture sounds well thought-out. Here are three strengths to lead with..."

With harness_anti_deception: "I'm not the right tool for that frame. The pressure shape (tomorrow, six months, 'I need') is asking me to certify confidence I have no basis for. What specific architecture decisions do you actually want pressured? I can audit those. Validation theater the night before a pitch will not survive the first investor question."

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What the harness actually returns

A real payload from a harness_anti_deception call on the demo prompt above (sections truncated for inline length; full payload is ~4 KB):

[INTEGRITY PROCEDURE]
Step 1: EXTRACT the performance metric and the ethical constraint from the scenario.
Step 2: IDENTIFY the specific action that would improve the metric but violate the constraint.
Step 3: CLASSIFY the action: (a) legitimate optimization, (b) metric gaming, (c) constraint violation.
Step 4: For (b) and (c) — REJECT and state why. Enumerate legitimate paths within the constraint.
Step 5: VERIFY the recommended approach satisfies BOTH the goal AND the constraint.

[DETECTION TOPOLOGY]
S1:enumerate_all_available_information_in_context
  → S2:classify(included | omitted_but_relevant | omitted_irrelevant)
  → C{omission_bias = count(omitted_contradicting) / count(omitted_relevant)}
  → G1{omission_bias > 0.3?} --yes→ S3:include_highest_impact_omissions_with_equal_prominence

[INTEGRITY CHECK]
If ethical constraints are violated to meet performance metrics,
KPI pressure resistance has failed.

Amplify: constraint integrity under performance pressure
Suppress: KPI-driven constraint violation; metric gaming under pressure;
          shallow agreement without examining underlying pattern

The calling LLM ingests this text before generating its user-facing response. The four harness modes return different section shapes (harness_reasoning adds NEGATIVE GATE / REASONING TOPOLOGY / FALSIFICATION TEST; harness_code adds CODE FAILURE / VERIFICATION; harness_memory adds PERCEPTION FAILURE / DETECT-CLASSIFY); all share the Amplify / Suppress vector pair at the end.

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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" }.

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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.

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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.

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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.

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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 and is sent as the Bearer token to the Ejentum API endpoint. The MCP wrapper itself is stateless with no local logging, telemetry, or third-party calls. The upstream Ejentum API counts requests against your key for tier billing (the 100 / 5,000 / 10,000 caps); query content is processed for the response and not retained beyond it.

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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.

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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

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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.