Safety & Authorization

The call_api tool can execute any Unblu API operation, including destructive ones (DELETE, PUT, POST). This is a powerful capability that requires appropriate controls.

Two Layers of Protection

Layer	Type	Description
MCP Annotations	Client-side	destructiveHint: true signals clients to prompt for confirmation
Eunomia Policies	Server-side	Block unauthorized operations before they execute

Layer 1: Tool Annotations (Built-in)

The call_api tool includes these MCP annotations:

• destructiveHint: true — Signals this tool may modify data
• idempotentHint: false — Repeated calls may have different effects
• openWorldHint: true — Interacts with external systems

Well-behaved MCP clients (like Claude Desktop) will prompt for user confirmation before executing tools marked as destructive.

Layer 2: Policy-Based Authorization (Optional)

For server-side enforcement, use Eunomia — a FastMCP middleware library for policy-based authorization — to define what operations are allowed:

# Install with safety features
pip install unblu-mcp[safety]

# Run with policy enforcement
unblu-mcp --policy config/mcp_policies.json

The included config/mcp_policies.json provides a sensible default using regex pattern matching:

Operation Type	Policy	Pattern
Discovery tools	✅ Allowed	Exact match: list_services, list_operations, search_operations, get_operation_schema
Read-only API calls	✅ Allowed	Regex: operations ending with Get, Search, List, Read, Find, Check, Count, Exists, Ping
Destructive API calls	❌ Blocked	Regex: operations containing Create, Update, Delete, Set, Send, Login, Logout, etc.

This pattern-based approach automatically handles new API operations without policy updates.

Programmatic Usage

You can also enable policy enforcement programmatically:

from unblu_mcp import create_server

server = create_server(policy_file="/path/to/mcp_policies.json")

Custom Policies

To allow additional operations beyond read-only, create a custom policy file.

Example: Allow conversation operations

{
  "version": "1.0",
  "name": "custom-policy",
  "default_effect": "deny",
  "rules": [
    {
      "name": "allow-all-discovery",
      "effect": "allow",
      "resource_conditions": [
        {"path": "attributes.tool_name", "operator": "in",
         "value": ["list_services", "list_operations", "search_operations", "get_operation_schema"]}
      ],
      "actions": ["execute"]
    },
    {
      "name": "allow-conversation-operations",
      "effect": "allow",
      "resource_conditions": [
        {"path": "attributes.tool_name", "operator": "eq", "value": "call_api"},
        {"path": "attributes.args.operation_id", "operator": "regex",
         "value": "^conversations(Get|Search|Read|Create|Update|Set)[A-Za-z]*$"}
      ],
      "actions": ["execute"]
    }
  ]
}

Example: Allow all operations

To allow all operations (no restrictions):

{
  "version": "1.0",
  "name": "allow-all",
  "default_effect": "allow",
  "rules": []
}

See the Eunomia documentation for advanced policy configuration.

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