LLM Council MCP

An MCP server that lets Claude Code consult external LLMs (GPT, Gemini) through multi-turn sessions. Get a second opinion, run parallel consultations, or do web-grounded research — all without leaving your Claude Code workflow.

Why?

Claude Code is powerful, but sometimes you want to:

• Get a second opinion on architecture decisions from GPT or Gemini

• Cross-reference answers by asking multiple models the same question

• Web-grounded research using Gemini's Google Search or OpenAI's web search

• Multi-turn conversations with external models while Claude orchestrates

This MCP server makes all of that possible with a simple tool interface.

Related MCP server: Senior Consult MCP

Tools

Supported Providers

Quick Start

1. Get API Keys

You need at least one:

• OpenAI: platform.openai.com/api-keys

• Gemini: aistudio.google.com/apikey

2. Add to Claude Code

Add this to your .mcp.json (in your home directory or project root):

{
  "mcpServers": {
    "llm-council": {
      "command": "uvx",
      "args": ["llm-council-mcp"],
      "env": {
        "OPENAI_API_KEY": "sk-...",
        "GEMINI_API_KEY": "AI..."
      }
    }
  }
}

Alternative — install locally with uv:

{
  "mcpServers": {
    "llm-council": {
      "command": "uv",
      "args": ["--directory", "/path/to/llm-council-mcp", "run", "python", "-m", "llm_council_mcp"],
      "env": {
        "OPENAI_API_KEY": "sk-...",
        "GEMINI_API_KEY": "AI..."
      }
    }
  }
}

3. Restart Claude Code

Claude Code will pick up the new MCP server on restart. You should see llm-council tools available.

Usage Patterns

Dispatching: Agent Teams or Background Subagents

Council tools are blocking calls (10-30s per response). Never call them from the main conversation. Two dispatch patterns:

Agent Teams (preferred in Claude Code): Use TeamCreate with one teammate per provider. Teammates can send real-time status updates via SendMessage -- errors surface immediately, results stream back as each provider responds.

Background Subagents (fallback): Use Agent with run_in_background=true, one per provider. Simpler but no intermediate status updates -- the caller only sees the final result.

User: "Ask GPT and Gemini what they think about this architecture"

Claude Code dispatches:
  -> Teammate/Agent 1: calls council(provider="openai", ...)
  -> Teammate/Agent 2: calls council(provider="gemini", ...)

Results arrive independently as each provider responds.

One Agent Per Provider

When consulting multiple providers, always use separate agents -- one per provider. This ensures the faster provider's results arrive immediately without waiting for the slower one.

Session Management

Sessions persist across calls within a conversation:

# First call creates the session
council(session="arch-review", message="Review this design...", provider="openai")

# Follow-up uses the same session (conversation continues)
council(session="arch-review", message="What about error handling?")

# Inject context without an LLM call
council_inject(session="arch-review", content="<file contents>", label="schema.sql")

# Clean up when done
council_delete(session="arch-review")

Web Research

# Stateless web-grounded research
council_research(query="What are the latest MCP server best practices?", provider="gemini")

Configuration

Environment Variables

You only need the API key for the provider(s) you use. If you only use Gemini, you don't need an OpenAI key (and vice versa). The key is loaded lazily when the provider is first called.

Default System Prompt

Create $LLM_COUNCIL_DATA_DIR/config.json to set a default system prompt applied to all sessions:

{
  "default_system_prompt": "You are a senior software architect. Be concise."
}

Custom system prompts passed to council() are appended after the default.

Error Handling

Council tools return errors as MCP CallToolResult with isError: true instead of throwing exceptions. This ensures the calling agent always gets a parseable result it can relay to the user.

Error responses include structured fields:

{
  "error": true,
  "provider": "gemini",
  "model": "gemini-3.1-pro-preview",
  "error_type": "RuntimeError",
  "phase": "headers",
  "retryable": true,
  "http_status": 503,
  "message": "Gemini API error 503: This model is currently experiencing high demand."
}

Streaming

Both providers use streaming HTTP (SSE) internally. This means:

• Instant error detection: HTTP errors (503, 429) surface immediately from response headers instead of hanging until a timeout fires.

• No arbitrary timeouts: The connection stays alive as long as the provider is generating tokens. No risk of cutting off legitimate long responses.

• Mid-stream resilience: If a connection drops after partial data, the error is reported with context about how much data was received.

Cost Tracking

Every council call returns usage stats including estimated cost:

{
  "provider": "openai",
  "model": "gpt-5.4",
  "session": "review-gpt",
  "response": "...",
  "usage": {
    "input_tokens": 1250,
    "output_tokens": 890,
    "reasoning_tokens": 2048,
    "cost_usd": 0.021
  }
}

Session-level cost tracking is available via council_sessions.

Development

# Clone and install
git clone https://github.com/Envious-Labs-LLC/llm-council-mcp.git
cd llm-council-mcp
uv sync

# Run directly
uv run python -m llm_council_mcp

# Test with MCP Inspector
npx @modelcontextprotocol/inspector uv run python -m llm_council_mcp

Adding a New Provider

1. Create src/llm_council_mcp/providers/yourprovider.py implementing LLMProvider

2. Add pricing to pricing.py

3. Add model profiles to model_profiles.py

4. Register in providers/__init__.py

License

MIT — see LICENSE.