Metis FCA Handbook AI Harness — MCP Server

An MCP (Model Context Protocol) server that integrates the Metis FCA Handbook AI Harness into your AI workflow. MCP is supported by Claude, OpenAI, Gemini, and most desktop/IDE MCP clients (Cursor, Windsurf, Cline, and others) — this README uses Claude Code and Claude Desktop as fully worked examples; adjust the configuration steps to fit your own client.

Source & full documentation: github.com/99blakeD99/the-metis-fca-handbook-ai-harness-mcp-files

Tools

evaluate_fca_handbook_applicability

Evaluate which FCA Handbook entries apply to an entity, via the Metis FCA Handbook AI Harness. One-shot: no session, no conversation state. Supports quick mode (60-120 seconds, default) and full mode (longer, more detailed). Returns a compliance report with verbatim citations, gaps, and refinement suggestions.

Related MCP server: eu-regulations

Why choose The Metis FCA Handbook AI Harness?

• Efficiency Multiplies effectiveness of compliance advice. Saves £80+ in token fees per Harness run.

• Deals with "Hard Problem", in which LLMs' token incentives prioritise training data so results are unreliable.

• Verbatim citations Quotes verbatim entries from the FCA Handbook. Other AI systems struggle to do this.

• Matches real-world need You do not have to start off knowing which sections you are looking for. Carries out structured searches across all 33,000+ FCA Handbook entries.

• Secure Design Harness compartmentalisation, one-shot structure, and statelessness fits natively with emerging AI agent security standards such as OWASP Top 10 for Agentic Applications 2026.

• AI Accessible Integrates easily with AI workflows and agents. Your LLM can use it as a tool.

Try the Harness Live

Experience the Harness interactively before integrating:

https://fcahandbookharnessimplementation.onrender.com

Email the-metis-fca-handbook-ai-harness@jbmd.co.uk and request a free temporary Access Code.

Ask compliance questions in natural language and watch each reasoning step unfold in real-time.

Design Principles

The Harness is built on proven principles:

• Stateless — Each request is independent; no session coupling

• One-shot — Complete analysis in a single call; no multi-turn state

• Clear contract — Explicit input/output schemas for easy integration

• Hosted — Single canonical source; no version drift or stale data

Use Cases

Compliance AI Platforms

Embed FCA reasoning as a service within your compliance platform. Users ask natural-language questions; your platform calls the Harness and presents structured reasoning.

AI Agent Workflows

Agents building compliance workflows can include FCA Handbook reasoning as a composed tool—no external API calls, just MCP configuration.

Compliance Review Automation

Integrate into document review or due-diligence pipelines. Automatically screen new rules against FCA applicability.

For Regulatory Screening

FS firms screening MCP servers will find:

• Simple model: Stateless, no hidden state, no background jobs

• Clear contract: Explicit input schema, output schema, error modes

• Transparent updates: Version pinning; no automatic upgrades

• Single point of failure: If the Harness is down, it is obvious; no cascading config issues

• Audit-friendly: All calls logged centrally, not distributed

Quick Start

1. Get an API Key

Visit the Metis account dashboard:

https://fcahandbookharnessimplementation.onrender.com

• Click "Create Account" (modal on the homepage)

• Complete Stripe payment flow (accounts are paid)

• Navigate to API Keys and generate a new key

• Save it securely

2. Install the MCP Server

pip install fca-handbook-harness-mcp

3. Configure your MCP client

The mcpServers JSON shape below is shared by most desktop/IDE MCP clients, but the config file location and restart step vary by client. Pick the one that matches what you are using.

Important: The Harness API key should be supplied at runtime from an environment variable or secrets manager, never hardcoded as a literal value in a configuration file that may be committed to a shared repository. Two methods are supported — pick one, since they require different MCP config:

• Method A — Shell Profile. Add export METIS_API_KEY="sk_live_..." to your shell startup file (~/.bashrc, ~/.zshrc, etc.), before launching your MCP client (VS Code, Claude Desktop, etc.), so the variable is present in the client's own process environment. With this method, your MCP config should reference the variable via substitution:

  "env": { "METIS_API_KEY": "${METIS_API_KEY}" }

• Method B — .env File. Create a .env file in your project directory containing METIS_API_KEY=sk_live_.... The server loads this itself at startup (via load_dotenv()) — your MCP client never needs to see the value. With this method, omit the env block from your MCP config entirely. Do not copy the "${METIS_API_KEY}" snippet from Method A — your client's own environment will not have that variable set, so the substitution will silently fail and pass the literal string ${METIS_API_KEY} through as your API key. This produces a 401 error that is easy to mistake for a bad/revoked key.

⚠️ If your MCP config lives in your home directory (~/.mcp.json) rather than a project-local location (.mcp.json in a project root), it applies to every project on the machine — a stray ${METIS_API_KEY} placeholder there will break the harness for every project, not just the one you are setting up. Prefer a project-local config unless you specifically want a shared, machine-wide key.

3a. Claude Code

Claude Code (the Claude IDE extension) supports both global (user-level) and project-level MCP configuration. Note: MCP servers are configured in .mcp.json files, never in .claude/settings.json — that file is for permissions/preferences only and does not recognize an mcpServers key (Claude Code will reject it with Unrecognized field: mcpServers).

The easiest way to add either scope is the CLI itself, which writes the correct file for you. Quote the ${METIS_API_KEY} reference exactly as shown (single quotes) so your shell does not expand it before claude mcp add sees it — otherwise your actual key gets written as a literal into the config file, which is the hardcoding this whole section is trying to avoid:

claude mcp add --scope user fca-handbook-harness-mcp -e 'METIS_API_KEY=${METIS_API_KEY}' -- fca-handbook-harness-mcp

This is Method A — export the real key in your shell profile as shown below. Use --scope project instead of --scope user for a project-local setup. If you would rather edit the file directly, or want Method B (.env), see below.

Global Configuration (Recommended for FS Firms)

If you work across multiple projects, configure the MCP globally so it is available everywhere. Because this file is shared machine-wide, use Method A — a stray .env lookup path is per-project and does not fit a global setup as cleanly.

File location: ~/.mcp.json (your home directory — note this is a standalone file, not inside .claude/)

Edit or create ~/.mcp.json and add:

{
  "mcpServers": {
    "fca-handbook-harness-mcp": {
      "command": "fca-handbook-harness-mcp",
      "env": {
        "METIS_API_KEY": "${METIS_API_KEY}"
      }
    }
  }
}

Then add to your shell profile (e.g. ~/.bashrc, ~/.zshrc, ~/.fish/config.fish), before starting Claude Code:

export METIS_API_KEY="sk_live_..."

Replace sk_live_... with your actual API key from your Metis account. Claude Code substitutes ${METIS_API_KEY} from this environment variable when it starts the server — if the variable is not set at that point, Claude Code loads the server with the literal string ${METIS_API_KEY} instead (and warns about it), which is what causes the misleading 401 described in Troubleshooting below.

Restart: Restart Claude Code. Once connected, the evaluate_fca_handbook_applicability tool will be available in all projects.

Project-Level Configuration (Single-Project Setup)

If you only need the MCP in one specific project, configure it project-locally instead. This is the natural fit for Method B.

File location: .mcp.json in your project root (a standalone file, not inside .claude/)

Edit or create .mcp.json and add — no env block, per Method B above:

{
  "mcpServers": {
    "fca-handbook-harness-mcp": {
      "command": "fca-handbook-harness-mcp"
    }
  }
}

Then create a .env file in your project root containing:

METIS_API_KEY=sk_live_...

Replace sk_live_... with your actual API key from your Metis account.

Important: Project-level .mcp.json and .env files are often checked into version control — ensure METIS_API_KEY is in .gitignore before committing (the .mcp.json itself contains no secret, since Method B omits the env block), or use the global configuration approach instead (recommended for FS firms).

Restart: Claude Code will detect the change and reload MCP connections automatically (or you can restart the IDE).

3b. Claude Desktop

File location:

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

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

• Linux: ~/.config/Claude/claude_desktop_config.json

Claude Desktop's config is inherently machine-wide (there is no project-local variant), so Method A is the more consistent fit — see the ⚠️ note above before using Method B here.

Method A — Shell Profile:

{
  "mcpServers": {
    "fca-handbook-harness-mcp": {
      "command": "fca-handbook-harness-mcp",
      "env": {
        "METIS_API_KEY": "${METIS_API_KEY}"
      }
    }
  }
}

Set METIS_API_KEY in your system environment (e.g. in ~/.bashrc, system preferences, or via GUI) before launching Claude Desktop:

export METIS_API_KEY="sk_live_..."

Method B — .env File: create a .env file in the directory Claude Desktop runs from, containing METIS_API_KEY=sk_live_..., and use the config above with the env block omitted entirely (not left in with the ${METIS_API_KEY} placeholder — see Method B warning above).

Restart: Quit and restart the Claude Desktop app. Once connected, the evaluate_fca_handbook_applicability tool will be available.

3c. Other Clients (Cursor, Windsurf, Cline, etc.)

These clients typically use the same mcpServers JSON shape as Claude Desktop above. Consult your client's documentation for the config file location, restart procedure, and whether it performs ${VAR} substitution in env blocks the way Claude Code and Claude Desktop do (some use GUI connectors rather than JSON files, or may not substitute at all — check before relying on Method A).

4. Verify the connection

Claude Code, first run only: the first time you launch claude (interactively, not with -p) in a project with a new or changed project-scoped .mcp.json, it shows a one-time trust/approval prompt for that server before connecting — until you accept it, the server sits in a "pending approval" state and its tool is not actually available (running claude mcp list will show ⏸ Pending approval). Accept the prompt, or run /mcp in an existing session to approve it there. This gate does not apply to ~/.mcp.json (global scope).

Once approved/restarted, you should see evaluate_fca_handbook_applicability available as a tool in your agent workflows. If it does not appear, check the Troubleshooting section below.

Using the Tool

The tool accepts two parameters:

• user_input (required, max 5000 characters): Everything together as one piece of text — firm type, products/services, target market, regulatory question, etc.

• analysis_mode (optional): "quick" (default, ~60-120 seconds) or "full" (longer, detailed conditional reasoning)

The tool returns:

• summary: 2-3 sentence overview of applicability

• entry_analysis: Retrieved FCA Handbook entries with reasoning

• obligations: High-confidence and low-confidence/tangential obligations, each optionally flagged with the specific condition under which it applies

• refinement_suggestions: What the analysis couldn't determine from your input and why it matters, paired with the specific edit to make to improve accuracy

• citations: Verbatim quotes from FCA Handbook with binding levels (R=Rule, G=Guidance)

• tokens: Object with input, output, and total token counts, for cost/complexity tracking

Troubleshooting

Claude Code: "Settings validation failed: Unrecognized field: mcpServers":

• This means mcpServers was added to .claude/settings.json (or ~/.claude/settings.json) — that file does not support it. Move the mcpServers block to .mcp.json (project-local) or ~/.mcp.json (global) instead, per 3a above, or run claude mcp add --scope project|user ... to have Claude Code write it for you.

Claude Code: the model seems vaguely aware "an MCP" exists but does not know its name or what it does, and never calls it:

• This is the first-run approval gate (see step 4 above), not a tool-description problem — an unapproved project-scoped .mcp.json server never actually connects, so the model never receives its real name/description/schema, only generic MCP-resource tools. Run claude mcp list to confirm (⏸ Pending approval means this is it), then run /mcp or restart claude interactively to approve it.

Tool not appearing (Claude Desktop; the same class of issue applies to most desktop MCP clients):

• Verify the config file path (platform-specific, see above)

• Confirm fca-handbook-harness-mcp resolves on the command line (which fca-handbook-harness-mcp / where fca-handbook-harness-mcp). Desktop MCP clients typically launch with a minimal environment and may not see the same PATH as your shell — if the command does not resolve, replace "command": "fca-handbook-harness-mcp" with the absolute path from that lookup

• Restart your MCP client (not just reload)

401 Unauthorized with a key you've confirmed is valid on the dashboard:

• Check whether your MCP config still contains a literal ${METIS_API_KEY} (or similar) placeholder that never got substituted — this happens when Method B (.env) is used but the config still has an env block written for Method A. Inspect the actual spawned server process's environment (e.g. /proc/<pid>/environ on Linux) to confirm what value it is really receiving

• Verify METIS_API_KEY is set — either in the config env (Method A) or in a .env file the server can find (Method B), not both and not neither

• Check the key is correct (copy from dashboard again)

• Ensure no extra spaces or newlines in the key

Connection timeout:

• The analysis can take 60-120 seconds (quick mode) or longer (full mode)

• Ensure you have internet access to fcahandbookharnessimplementation.onrender.com

Files

• mcp_server.py — MCP server implementation (main entry point; its docstring is the source of truth for the tool schema)

• pyproject.toml — pypi package manifest

• server.json — MCP registry manifest (registry.modelcontextprotocol.io format)

• manifest.json — MCPB/Smithery bundle manifest

• requirements.txt — Python dependencies (mcp, requests)

• uv.lock — Pinned dependency resolution for reproducible uv run

• __init__.py — Python package marker

• README.md — This file

• LICENSE — MIT License

• .gitignore — Git ignore rules

• .mcpbignore — Files excluded from the MCPB bundle

Support

For questions or issues, contact: the-metis-fca-handbook-ai-harness@jbmd.co.uk

Product: Metis FCA Handbook AI Harness
License: MIT