A2A protocol

The A2A protocol is organised as a stack of composable standards. At the base is a governance layer covering versioning, conformance rules, and alignment to external standards including Polaris UK for code lists, Defaqto for product taxonomy, FCA rules for conduct, and UK GDPR for data handling.

Above the governance layer are three planes that apply across all lines of business. Plane 1, Interactions, defines the lifecycle of interactions an agent can have: Inform, New Business, Mid-Term Adjustment, Renewal, Claims, Cancellation, and Servicing. Plane 2, Information, classifies the types of data an agent can read by access authority: Public, Policyholder-authenticated, Consented enrichment, Derived, and Regulatory disclosure. Plane 3, Core Patterns, defines the cross-cutting behavioural rules every conformant agent must follow: grounding and no-fabrication, assume-infer-confirm, the advice-versus-information boundary, disclose-and-acknowledge, honest absence, data protection, vulnerability and Consumer Duty, handover, and audit.

Line-of-business standards sit on top of these three planes. The Home standard (buildings and contents) is live in production with a Tier-1 UK carrier at version 1.0. Motor is at hardened draft v0.2. SMB commercial lines, pet, and travel are at draft v0.1.

The protocol is published as an open standard; Marrow stewards the drafting but does not assert proprietary control over the interface. Carriers, AI platforms, and regulators are invited to participate in its development. The protocol is also referred to informally as the Marrow Protocol, reflecting Marrow's role as steward.