Authorized Properties

One of the foundational challenges in digital advertising is unauthorized resale - ensuring that sales agents are actually authorized to represent the advertising properties they claim to sell. AdCP solves this problem through a comprehensive authorization system that builds on the lessons learned from ads.txt in programmatic advertising.

New to AdCP authorization? Read AdCP Basics: Authorized Properties for an accessible introduction to how authorization works in agentic advertising.

The Problem: Unauthorized Resale

Historical Context

In programmatic advertising, the Ads.txt initiative was created to solve a critical problem: unauthorized reselling of advertising inventory. Before ads.txt, bad actors could claim to represent popular websites and sell their inventory without permission, leading to:

Revenue theft: Publishers lost money to unauthorized sellers
Brand safety issues: Buyers couldn’t verify legitimate inventory sources
Market fragmentation: No way to distinguish authorized from unauthorized sellers

The Same Problem in AI-Powered Advertising

AdCP faces similar challenges as AI agents begin to buy and sell advertising programmatically:

AI sales agents may claim to represent properties they don’t actually control
Buyer agents need to verify authorization before making purchases
Publishers need a way to explicitly authorize specific sales agents
Scale challenges: Manual verification doesn’t work for networks with thousands of properties

The Solution: AdCP Authorization System

AdCP prevents unauthorized resale through a two-part system:

Publisher Authorization: Publishers explicitly authorize sales agents via adagents.json
Agent Discovery: Sales agents declare their authorized properties via list_authorized_properties

This creates a verifiable chain of authorization that buyer agents can validate.

How Publishers Authorize Sales Agents

Publishers authorize sales agents by hosting an adagents.json file at /.well-known/adagents.json on their domain. This file lists all authorized agents and their permissions.

Example adagents.json

{
  "$schema": "https://adcontextprotocol.org/schemas/v2/adagents.json",
  "contact": {
    "name": "Sports Network Media",
    "email": "adops@sportsnetwork.com",
    "domain": "sportsnetwork.com"
  },
  "properties": [
    {
      "property_id": "sports_network_main",
      "property_type": "website",
      "name": "Sports Network",
      "identifiers": [
        {"type": "domain", "value": "sportsnetwork.com"}
      ],
      "tags": ["premium", "sports"]
    }
  ],
  "authorized_agents": [
    {
      "url": "https://sports-media-sales.com",
      "authorized_for": "All Sports Network properties",
      "authorization_type": "property_tags",
      "property_tags": ["sports"]
    },
    {
      "url": "https://premium-ad-network.com",
      "authorized_for": "Premium inventory only",
      "authorization_type": "property_tags",
      "property_tags": ["premium"]
    }
  ],
  "last_updated": "2025-01-10T12:00:00Z"
}

Key Fields

contact: Identifies the publisher/entity managing this file
properties: Defines the properties covered by this authorization file
authorized_agents: List of sales agents authorized to represent properties
- url: Agent’s API endpoint URL
- authorized_for: Human-readable description of authorization scope
- authorization_type: How properties are selected (property_ids, property_tags, inline_properties, publisher_properties)
last_updated: ISO 8601 timestamp of last modification

Sales agents use the list_authorized_properties task to declare all properties they are authorized to represent. This serves multiple purposes:

Transparency: Buyers can see what properties an agent represents
Validation enablement: Provides the data buyers need to verify authorization
Tag resolution: Enables efficient grouping of properties by tags

Property Declaration Example

{
  "properties": [
    {
      "property_type": "website",
      "name": "Sports Network",
      "identifiers": [
        {"type": "domain", "value": "sportsnetwork.com"}
      ],
      "tags": ["sports_network", "premium"],
      "publisher_domain": "sportsnetwork.com"
    },
    {
      "property_type": "radio",
      "name": "WXYZ-FM Chicago",
      "identifiers": [
        {"type": "call_sign", "value": "WXYZ-FM"},
        {"type": "market", "value": "chicago"}
      ],
      "tags": ["local_radio", "midwest"],
      "publisher_domain": "radionetwork.com"
    }
  ],
  "tags": {
    "sports_network": {
      "name": "Sports Network Properties",
      "description": "145 sports properties and networks"
    },
    "local_radio": {
      "name": "Local Radio Stations",
      "description": "1847 local radio stations across US markets"
    }
  },
  "advertising_policies": "We maintain strict brand safety standards. Prohibited categories include: tobacco and vaping products, online gambling and sports betting, cannabis and CBD products, political advertising, and speculative financial products (crypto, NFTs, penny stocks).\n\nWe also prohibit misleading tactics such as clickbait headlines, false scarcity claims, hidden pricing, and ads targeting vulnerable populations.\n\nCompetitor brands in the streaming media space are blocked by policy.\n\nFull advertising guidelines: https://publisher.com/advertising-policies"
}

Property Tags for Scale

For large networks representing thousands of properties, AdCP supports property tags to make the system manageable:

Products can reference ["local_radio", "midwest"] instead of listing hundreds of stations
Buyers use list_authorized_properties to resolve tags to actual properties
Authorization validation works on the resolved properties

Authorization Validation Workflow

Here’s how a buyer agent validates that a sales agent is authorized to represent claimed properties:

1. One-Time Setup

// Get all properties the sales agent claims to represent
const response = await salesAgent.call('list_authorized_properties');
const allProperties = response.properties;

// For each unique publisher domain, fetch and cache adagents.json
const domains = [...new Set(allProperties.map(p => p.publisher_domain))];
const authorizationCache = {};

for (const domain of domains) {
  try {
    const adagents = await fetch(`https://${domain}/.well-known/adagents.json`);
    authorizationCache[domain] = await adagents.json();
  } catch (error) {
    console.warn(`Could not verify authorization for ${domain}`);
    authorizationCache[domain] = null;
  }
}

2. Product Validation

// When evaluating a product
const product = await salesAgent.call('get_products', {brief: "Chicago radio ads"});

// Validate authorization for each publisher in publisher_properties
const authorized = product.publisher_properties.every(pubProp => {
  const domain = pubProp.publisher_domain;
  const adagents = authorizationCache[domain];

  if (!adagents) return false; // No adagents.json found

  // Get properties from this publisher
  const publisherProps = allProperties.filter(p => p.publisher_domain === domain);

  // Resolve property_tags to actual properties if needed
  let propertiesToCheck = pubProp.property_ids
    ? publisherProps.filter(p => pubProp.property_ids.includes(p.property_id))
    : publisherProps.filter(p => pubProp.property_tags.every(tag => p.tags.includes(tag)));

  // Validate authorization for these properties
  return propertiesToCheck.every(property =>
    adagents.authorized_agents.some(agent =>
      agent.agent_id === salesAgent.id && 
    isCurrentlyAuthorized(agent.authorization_scope)
  );
});

if (!authorized) {
  throw new Error("Sales agent not authorized for claimed properties");
}

3. Ongoing Validation

Cache adagents.json responses with reasonable TTL (e.g., 24 hours)
Re-validate periodically for long-running campaigns
Handle authorization changes gracefully (pause vs. reject)

Benefits of This Approach

For Publishers

Explicit control over who can sell their inventory
Granular permissions by property, date range, and product type
Standard web hosting - no special infrastructure required
Audit trail of authorized agents

For Sales Agents

Clear authorization proof that buyers can verify
Efficient tag-based grouping for large property portfolios
Standardized declaration across all AdCP interactions

For Buyer Agents

Automated verification of seller authorization
Fraud prevention through cryptographic verification
Confidence in purchases from verified inventory sources
Scalable validation for large-scale automated buying

Security Considerations

Domain Verification

HTTPS required: adagents.json must be served over HTTPS
Domain ownership: Only domain owners can authorize agents for their properties
Regular validation: Buyers should re-check authorization periodically

Authorization Scope

Least privilege: Grant minimal necessary permissions
Time bounds: Use start/end dates for temporary authorizations
Property restrictions: Limit to specific paths or property types when appropriate

Error Handling

Missing adagents.json: Treat as unauthorized (fail closed)
Invalid JSON: Reject malformed authorization files
Network errors: Implement retry logic with fallback policies
Expired authorization: Handle gracefully in active campaigns

Integration with Product Discovery

Authorization validation integrates seamlessly with Product Discovery:

Discover products using get_products
Validate authorization for properties referenced in products
Proceed confidently with authorized inventory
Flag unauthorized products for manual review

This creates a trustworthy foundation for AI-powered advertising that prevents unauthorized resale while enabling efficient, automated transactions.

Technical Implementation

For complete technical details on implementing the adagents.json file format, including:

File location and format requirements (/.well-known/adagents.json)
JSON schema definitions and validation rules
Mobile application and CTV implementation patterns
Detailed property type specifications (website, mobile app, CTV, DOOH, podcast)
Domain matching rules and wildcard patterns
Validation code examples and error handling
Security considerations and best practices

See the adagents.json Tech Spec for complete implementation guidance.

list_authorized_properties - API reference for property discovery
Product Discovery - How authorization integrates with product discovery
Properties Schema - Technical property data model
adagents.json Tech Spec - Complete adagents.json implementation guide

Getting Started

Protocols

Signals

Curation Protocol

Media Buy

Creative

Reference

Community

The Problem: Unauthorized Resale

Historical Context

The Same Problem in AI-Powered Advertising

The Solution: AdCP Authorization System

How Publishers Authorize Sales Agents

Example adagents.json

Key Fields

Property Declaration Example

Property Tags for Scale

Authorization Validation Workflow

1. One-Time Setup

2. Product Validation

3. Ongoing Validation

Benefits of This Approach

For Publishers

For Sales Agents

For Buyer Agents

Security Considerations

Domain Verification

Authorization Scope

Error Handling

Integration with Product Discovery

Technical Implementation

​The Problem: Unauthorized Resale

​Historical Context

​The Same Problem in AI-Powered Advertising

​The Solution: AdCP Authorization System

​How Publishers Authorize Sales Agents

​Example adagents.json

​Key Fields

​How Sales Agents Share Authorized Properties

​Property Declaration Example

​Property Tags for Scale

​Authorization Validation Workflow

​1. One-Time Setup

​2. Product Validation

​3. Ongoing Validation

​Benefits of This Approach

​For Publishers

​For Sales Agents

​For Buyer Agents

​Security Considerations

​Domain Verification

​Authorization Scope

​Error Handling

​Integration with Product Discovery

​Technical Implementation

​Related Documentation

The Problem: Unauthorized Resale

Historical Context

The Same Problem in AI-Powered Advertising

The Solution: AdCP Authorization System

How Publishers Authorize Sales Agents

Example adagents.json

Key Fields

How Sales Agents Share Authorized Properties

Property Declaration Example

Property Tags for Scale

Authorization Validation Workflow

1. One-Time Setup

2. Product Validation

3. Ongoing Validation

Benefits of This Approach

For Publishers

For Sales Agents

For Buyer Agents

Security Considerations

Domain Verification

Authorization Scope

Error Handling

Integration with Product Discovery

Technical Implementation

Related Documentation