Agentic Interaction Standards: MCP, A2A, AdCP, UCP, and More

Anthropic’s Model Context Protocol (MCP) was launched in November 2024 and is now governed by the Linux Foundation. MCP lets AI agents built on large language models connect to external data sources or servers by acting as a universal adapter. In April 2025 Google introduced the Agent‑to‑Agent Protocol (A2A), also Linux‑Foundation‑managed, which enables agents to communicate without exposing internal logic and is adopted by Microsoft, AWS, SAP, Salesforce and IBM. October 2025 saw the creation of the Ad Context Protocol (AdCP) by a consortium including Yahoo, PubMatic and Optable, built on MCP to standardise agentic media buying. The same month, IAB Tech Lab released the Agentic RTB Framework (ARTF) in November 2025, a containerised framework that lets agents operate inside existing SSP/DSP environments with lower‑latency auctions. LiveRamp’s User Context Protocol, renamed Agentic Audiences, provides a privacy‑safe way for agents to exchange user‑level embeddings and has been integrated with OpenRTB and Prebid. OpenAI and Stripe launched the Agentic Commerce Protocol (ACP) in September 2025 alongside ChatGPT’s Instant Checkout, enabling agents to verify payment details and confirm orders. In January 2026 Google, in partnership with iShopify, Etsy, Wayfair, Target and Walmart, debuted the Universal Commerce Protocol (UCP), the most widely adopted commerce standard that interops with MCP, A2A and AP2. Google’s Agent Payments Protocol (AP2), created with Coinbase, PayPal, Mastercard and others, adds a cryptographically‑signed mandate layer for secure user‑authorised purchases. Finally, Coinbase and Cloudflare introduced the x402 stable‑coin payment rail, and Visa’s Trusted Agent Protocol (TAP) was released in October 2025 to authenticate agents for merchants.