NEXUS LEGAL × MCP

Your Claude now speaks the law of 36 jurisdictions.

Official Nexus Legal MCP server. Connect in 2 minutes and start invoking ISO 31000 analysis, cross-audit, brief drafting, Monte Carlo simulation, multi-jurisdictional doctrine search, case-law search across 36 countries and international organizations, adversarial red team, multi-LLM second opinion and cross-border comparison — all from your Claude chat.

Get my MCP key →How it works ↓
Claude Desktop · Claude Code · Cursor · Cline · ZedGDPR Compliant · Zero Retention · EU-hostedPay per use · no annual subscriptionOpen source (MIT)

WHAT IS MCP

One interface. Eleven legal capabilities.

What is the Model Context Protocol?

MCP is the open standard, published by Anthropic in 2024, that lets an AI client (like Claude Desktop) discover and use external tools with user permission. Think of it as plugins for AI assistants: the client remains Claude; the tools can come from specialised third parties. Nexus Legal exposes its 11 legal capabilities as an MCP server — meaning any lawyer already using Claude Desktop, Claude Code or Cursor can start requesting specialised legal analysis from their regular chat, without opening a browser, without copy-pasting a contract twice, without switching apps.

Before: Claude thinks in general, Nexus thinks in law. You had to switch between them for each contract.

Now: you talk to Claude. When your query requires jurisdictional rigour, Claude offers to invoke Nexus automatically. Nexus responds with defensible certainty locks across 36 covered jurisdictions. Claude integrates the answer into the conversation.

11 LEGAL CAPABILITIES

What you can ask Claude to do

Each tool is invoked by Claude when the query matches — or you can call them explicitly.

nexus_analyze

Primary ISO 31000 Analysis

Full analysis of contracts, briefs, rulings and orders with certainty locks [L1]–[L5] and a NEXUS-AUDIT-TRAIL block.

nexus_consulta

Free Legal Query

Natural-language question with or without a context document. Supports multi-turn conversational threads.

nexus_draft

Brief Drafting

Generates a first draft of an appeal, complaint, reply, clause or opinion following the MODULE-DRAFT format.

nexus_audit

Node B Cross-Audit

Re-examines a Node A analysis against the source document. Detects unsupported claims, mis-assigned locks, omissions and contradictions.

nexus_monte_carlo

Scenario Simulation

Stress-tests the risk profile under defined variables. Calculates a Contractual Resilience Index 0–100. Ideal for M&A and due diligence.

nexus_doctrina

Multi-Jurisdiction Regulatory Doctrine

Searches the curated corpus of binding regulatory rulings, tax authority resolutions, council of state opinions and equivalent criteria across supported jurisdictions. For fiscal and regulatory questions.

nexus_opinion

Multi-LLM Second Opinion

Takes a Node A response and re-examines it with a different LLM looking for omissions, biases and errors. For high-stakes cases.

nexus_redteam

Adversarial Red Team

Hostile analysis as opposing counsel: legal gaps, trap clauses, catastrophic risks. Structured JSON output.

nexus_adversarial

Adversarial Argumentation

For each conclusion of analysis A, builds the strongest argument the opposing party would raise. To prepare for litigation.

nexus_cross_border_compare

Multi-Jurisdiction Comparison

Compares how each legal system (2–15 countries) treats the given facts or contract. For clients operating across borders.

nexus_jurisprudencia_search

Jurisprudence Search

Vector search across the curated multi-jurisdiction corpus — hundreds of thousands of rulings covering 36 countries and international organizations. Locate case law on a specific topic. Free.

WHY NEXUS MCP

Built for jurisdictions Claude doesn't know

Beyond Claude alone

Claude Pro/Teams excels at general legal reasoning. But it has no curated jurisdictional corpus and no certainty locks defensible before a professional body. Nexus adds exactly that: 36 jurisdiction modules + curated corpus + immutable audit trail + Node B cross-audit.

36 jurisdictions vs. 12 English-only plugins

The 12 plugins Anthropic announced for 'Claude for Legal' are US-centric: US Litigation, US Corporate, US Privacy. Nexus covers hand-curated modules across 36 countries and international organizations — spanning Latin America, Europe, Asia-Pacific, Africa and supranational bodies (EU, ECHR, IACtHR, ICC and others). The only serious option if you litigate or advise across borders.

Pay per use. No annual commitment.

Comparable suites charge €10–50k per year. Nexus is pay-per-use, installed in 2 minutes, no annual commitment. For a firm not ready to commit long-term, Nexus is the ideal on-ramp: try it, scale it, decide.

EU soil. Zero Retention by default.

We process in RAM in the Netherlands (Railway europe-west4) and do NOT persist documents to a database. For public-sector or sensitive clients, being able to certify Zero Retention on EU soil is a blocking requirement. Nexus can prove no sensitive data ever leaves EU jurisdiction.

GET STARTED

Connected in 3 steps. 2 minutes.

01

Generate your MCP key (30 sec)

Go to nexusquantum.legal/developers, click '+ Create key', choose 'MCP Server', name it and click Create. Copy the nlk_... key. Shown only once.

02

Paste the config in your client (60 sec)

Add the block below to your client config file. Claude Desktop (Mac): ~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json · Claude Code: run claude mcp add nexus-legal -- npx -y @nexus-legal/mcp

03

Restart and start asking (30 sec)

Claude Desktop shows a 🔌 icon with 11 Nexus tools available. Try: 'Analyse this contract with Nexus, ES jurisdiction, conservative profile.' or 'Search TS case law on unfair floor clauses.'

claude_desktop_config.json
{
  "mcpServers": {
    "nexus-legal": {
      "command": "npx",
      "args": ["-y", "@nexus-legal/mcp"],
      "env": {
        "NEXUS_API_KEY": "nlk_TU_CLAVE_AQUI"
      }
    }
  }
}

USE CASES

How lawyers use it every day

S
Sarah
General practice lawyer

Receives a 40-page distribution contract at 6:30 pm for signature tomorrow. Before: opens Nexus web, uploads PDF, waits for analysis, downloads it, opens in Word, annotates. 25 minutes.

Now: drags the PDF to Claude Desktop, types 'analyse with Nexus, ES, conservative profile'. 2 minutes later she has the full report in chat with [L5-C] locks on the 3 critical clauses. Done in 8 minutes.

J
James
M&A associate

Preparing a bilateral SPA Spain–Mexico. Needs: choice-of-law comparison, CDI verification, red team on indemnification clauses, Monte Carlo simulation. Before: 4 different tools, 4 logins, 4 lost contexts.

Four MCP tools chained from Claude Code, where he was already drafting. One conversation. Done.

FAQ

Frequently asked questions

Nexus is already in your Claude.

Add 11 specialised legal capabilities to your existing workflow. No annual contract, no new interface to learn.

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@nexus-legal/mcp · MIT · v0.1.2 · github ↗