# Configuration
<p align="center">
<img src="../assets/docs-configuration.jpg" alt="Configuration - ducks tuning settings" width="600">
</p>
MCP Rubber Duck can be configured via environment variables or a JSON configuration file.
## Method 1: Environment Variables
Create a `.env` file in the project root:
```env
# OpenAI
OPENAI_API_KEY=sk-...
OPENAI_DEFAULT_MODEL=gpt-5.1 # Optional: defaults to gpt-5.1
# Google Gemini
GEMINI_API_KEY=...
GEMINI_DEFAULT_MODEL=gemini-2.5-flash # Optional: defaults to gemini-2.5-flash
# Groq
GROQ_API_KEY=gsk_...
GROQ_DEFAULT_MODEL=llama-3.3-70b-versatile # Optional: defaults to llama-3.3-70b-versatile
# Ollama (Local)
OLLAMA_BASE_URL=http://localhost:11434/v1 # Optional
OLLAMA_DEFAULT_MODEL=llama3.2 # Optional: defaults to llama3.2
# Custom Providers (you can add multiple)
# Format: CUSTOM_{NAME}_* where NAME becomes the provider key (lowercase)
# Example: Add provider "myapi"
CUSTOM_MYAPI_API_KEY=...
CUSTOM_MYAPI_BASE_URL=https://api.example.com/v1
CUSTOM_MYAPI_DEFAULT_MODEL=custom-model # Optional
CUSTOM_MYAPI_MODELS=model1,model2 # Optional: comma-separated list
CUSTOM_MYAPI_NICKNAME=My Custom Duck # Optional: display name
# Example: Add provider "azure"
CUSTOM_AZURE_API_KEY=...
CUSTOM_AZURE_BASE_URL=https://mycompany.openai.azure.com/v1
# CLI Providers (coding agents as ducks)
# Enable preset CLI agents
CLI_CLAUDE_ENABLED=true # Claude Code CLI
CLI_CODEX_ENABLED=true # OpenAI Codex CLI
CLI_GEMINI_ENABLED=true # Gemini CLI
CLI_GROK_ENABLED=true # Grok CLI
CLI_AIDER_ENABLED=true # Aider
# Optional overrides for preset CLI agents
CLI_CLAUDE_NICKNAME=My Claude # Optional: display name
CLI_CLAUDE_DEFAULT_MODEL=claude-sonnet-4-20250514 # Optional: model override
CLI_CLAUDE_SYSTEM_PROMPT=Be concise # Optional: system prompt
CLI_CLAUDE_CLI_ARGS=--max-turns,5,--verbose # Optional: extra CLI args
# Custom CLI providers (any CLI tool)
CLI_CUSTOM_MYTOOL_COMMAND=/usr/local/bin/mytool
CLI_CUSTOM_MYTOOL_NICKNAME=My Tool
CLI_CUSTOM_MYTOOL_PROMPT_DELIVERY=stdin # flag, positional, or stdin
CLI_CUSTOM_MYTOOL_OUTPUT_FORMAT=text # text, json, or jsonl
CLI_CUSTOM_MYTOOL_PROCESS_TIMEOUT=60000 # Optional: ms (default: 120000)
CLI_CUSTOM_MYTOOL_WORKING_DIRECTORY=/tmp # Optional: working directory
# Global Settings
DEFAULT_PROVIDER=openai
DEFAULT_TEMPERATURE=0.7
LOG_LEVEL=info
# MCP Bridge Settings (Optional)
MCP_BRIDGE_ENABLED=true # Enable ducks to access external MCP servers
MCP_APPROVAL_MODE=trusted # always, trusted, or never
MCP_APPROVAL_TIMEOUT=300 # seconds
# MCP Server: Context7 Documentation (Example)
MCP_SERVER_CONTEXT7_TYPE=http
MCP_SERVER_CONTEXT7_URL=https://mcp.context7.com/mcp
MCP_SERVER_CONTEXT7_ENABLED=true
# Per-server trusted tools
MCP_TRUSTED_TOOLS_CONTEXT7=* # Trust all Context7 tools
# Optional: Custom Duck Nicknames (Have fun with these!)
OPENAI_NICKNAME="DUCK-4" # Optional: defaults to "GPT Duck"
GEMINI_NICKNAME="Duckmini" # Optional: defaults to "Gemini Duck"
GROQ_NICKNAME="Quackers" # Optional: defaults to "Groq Duck"
OLLAMA_NICKNAME="Local Quacker" # Optional: defaults to "Local Duck"
# For custom providers, use: CUSTOM_{NAME}_NICKNAME (see custom provider section above)
```
**Note:** Duck nicknames are completely optional! If you don't set them, you'll get the charming defaults (GPT Duck, Gemini Duck, etc.). If you use a `config.json` file, those nicknames take priority over environment variables.
## Method 2: Configuration File
Create a `config/config.json` file based on the example:
```bash
cp config/config.example.json config/config.json
# Edit config/config.json with your API keys and preferences
```
See also: [CLI Providers](./cli-providers.md) for CLI-specific configuration, [MCP Bridge](./mcp-bridge.md) for bridge settings, [Guardrails](./guardrails.md) for safety configuration.
