policy-validation

Policy Validation: Security Rules and Enforcement

This skill teaches you Matimo's security policy engine—a developer-controlled, object-frozen, non-bypassable system that blocks dangerous tool patterns before they execute.

Core Principle: Policy is Immutable

Once the developer initializes Matimo with a policy configuration, that policy is frozen and cannot be changed by agents. This ensures:

• ✅ Agents cannot weaken security rules
• ✅ Agents cannot bypass domain restrictions
• ✅ Agents cannot create shell commands if blocked
• ✅ Policy is transparent and auditable

// At deploy time, developer sets immutable policy:
const policyConfig: PolicyConfig = {
  allowedDomains: ['api.github.com', 'api.weatherapi.com'],
  allowedHttpMethods: ['GET', 'POST'],
  allowCommandTools: false,
  allowFunctionTools: false,
  protectedNamespaces: ['matimo_'],
  allowedCredentials: ['GITHUB_TOKEN', 'WEATHER_API_KEY']
};

Object.freeze(policyConfig);  // ← Now immutable

// Agent cannot change this, even if it tries
// All tools are validated against this frozen policy

The matimo_doctor Meta-Tool

matimo_doctor is the policy validator. It checks tool definitions against:

1. Schema validation — YAML structure is correct
2. Policy validation — Tool complies with security rules

Input:  YAML tool definition (string)
Output: { valid: true, ... }  ✅ Safe to use
    OR: { valid: false, schemaErrors: [...], policyErrors: [...] }  ❌ Blocked

Example: Valid Tool → Passes Both Checks

name: github_user_lookup
version: "1.0.0"
description: Look up a GitHub user
parameters:
  username:
    type: string
    required: true
execution:
  type: http
  method: GET
  url: "https://api.github.com/users/{username}"

matimo_doctor result:

{
  "valid": true,
  "schemaErrors": [],
  "policyErrors": []
}

Example: Invalid YAML → Schema Error

name: my_tool
# Missing: version, description, parameters, execution