MCP Secrets

A secure secrets management MCP server for AI assistants. Enables LLM-powered CLI tools to safely handle credentials with user approval, automatic redaction, and secret capture from command output.

Features

Secret Injection - Use {{SECRET_NAME}} placeholders in commands to inject secrets
Session-Based Permissions - User approves secret access per-session with time-based expiry
Output Redaction - Automatically redacts known secrets and common patterns from output
Secret Capture - Extract secrets from command output (e.g., AWS session tokens) and store for future use
LLM-Friendly Metadata - Descriptions help future LLMs discover and use the right secrets
macOS Menu Bar App - Native notifications and dialogs for secret requests
Encrypted Vault - Secrets stored with Fernet encryption, key in system keychain

Installation

pip install mcp-secrets

Or install from source:

git clone https://github.com/henghonglee/mcp-secrets.git
cd mcp-secrets
pip install -e .

Quick Start

# Initialize the vault
mcp-secrets init

# Add a secret with description (helps LLMs understand what it's for)
mcp-secrets add AWS_ACCESS_KEY

# Start the MCP server
mcp-secrets serve

# Or run the menu bar app (macOS)
mcp-secrets-menubar

MCP Configuration

Add to your MCP client configuration:

{
  "mcpServers": {
    "secrets": {
      "command": "mcp-secrets",
      "args": ["serve"]
    }
  }
}

MCP Tools

`run_command`

Execute a CLI command with secret injection and output redaction.

{
  "command": "aws s3 ls --profile {{AWS_PROFILE}}",
  "timeout": 60,
  "capture": [
    {
      "path": "$.Credentials.SecretAccessKey",
      "name": "AWS_SESSION_SECRET",
      "description": "Temporary AWS secret key from STS. Use with AWS_SESSION_KEY_ID and AWS_SESSION_TOKEN.",
      "expires_at": "2024-01-24T12:00:00Z"
    }
  ]
}

Parameters:

command - Command with {{SECRET_NAME}} placeholders
timeout - Timeout in seconds (default: 60)
capture - Extract secrets from JSON output:
- path - JSONPath expression (e.g., $.Credentials.SecretAccessKey)
- name - Name for the captured secret
- description - LLM-friendly description
- expires_at - ISO 8601 expiration timestamp
redact_patterns - Additional regex patterns to redact
skip_builtin_patterns - Skip built-in redaction patterns

`list_secrets`

List available secrets with their descriptions.

{
  "tag": "aws"
}

Returns:

{
  "secrets": [
    {
      "name": "AWS_ACCESS_KEY",
      "description": "AWS access key for production account",
      "expires_at": null
    }
  ]
}

`request_secret`

Request the user to add a missing secret via the menu bar app.

{
  "name": "GITHUB_TOKEN",
  "description": "Personal access token for GitHub API. Needs repo and workflow scopes."
}

The menu bar app will show a native macOS dialog prompting the user to enter the secret value.

`get_permissions`

Get current session permission status for secrets.

How It Works

Client LLM calls list_secrets to discover available secrets
LLM constructs command with {{SECRET_NAME}} placeholders
User approves secret access when prompted (cached for session)
Server injects secrets and executes command
Output is redacted before returning to LLM
Captured secrets are stored with LLM-provided descriptions for future use

Menu Bar App (macOS)

The menu bar app provides:

Server status indicator (🔐 running / 🔓 stopped)
List of stored secrets with expiry times
Native dialogs for secret requests
Notifications when secrets are captured or expiring

Start with:

mcp-secrets-menubar

Security Model

Encrypted storage - Vault encrypted with Fernet, key stored in system keychain
Permission prompts - User must approve each secret's use
Session expiry - Permissions auto-expire (default: 1 hour)
Output redaction - Secrets automatically removed from command output
Audit logging - All secret access logged to ~/.mcp-secrets/audit.log

Configuration

Configuration stored at ~/.mcp-secrets/config.json:

{
  "session_timeout": 3600
}

Set values with:

mcp-secrets config set session_timeout 7200

Development

# Install dev dependencies
pip install -e ".[dev]"

# Run tests
pytest

# Run with coverage
pytest --cov=mcp_secrets

License

MIT

mcp-secrets