Group Type
Working GroupMission Statement
The Triggers and Events Working Group exists to define how MCP servers proactively notify clients of state changes. Today, clients learn about server-side updates by polling or holding an SSE connection open. This WG will specify a standardized callback mechanism—webhooks or similar—that lets servers push notifications when new data is available, with defined ordering guarantees that hold across all transports.Scope
In Scope
- Specification Work: SEPs defining the trigger/callback mechanism, subscription lifecycle, delivery semantics, and event ordering guarantees.
- Reference Implementations: SDK components demonstrating server-initiated notifications and client-side callback handling.
- Cross-Cutting Concerns: Coordination with the Transports WG on transport-specific delivery behavior, and with the Agents WG where task completion notifications intersect with event triggers.
- Documentation: Specification sections covering event-driven patterns and migration guidance from polling-based approaches.
Out of Scope
- Changes to the transport wire format or session model (owned by the Transports WG).
- General-purpose pub/sub infrastructure beyond what the MCP protocol requires.
- Modifications to existing notification primitives (
notifications/resources/updated,notifications/tools/list_changed, etc.) that do not relate to proactive server-initiated delivery.
Related Groups
- Transports WG — delivery and ordering guarantees depend on transport capabilities; callback semantics must be coherent across stdio, Streamable HTTP, and future transports.
- Agents WG — SEP-1686 (Tasks) identifies webhook-style task completion notifications as a future consideration; this WG owns that mechanism.
Leadership
| Role | Name | Organization | GitHub | Term |
|---|---|---|---|---|
| Lead | Clare Liguori | Amazon Web Services | @clareliguori | Initial |
| Lead | Peter Alexander | Anthropic | @pja-ant | Initial |
Authority & Decision Rights
| Decision Type | Authority Level |
|---|---|
| Meeting logistics & scheduling | WG Leads (autonomous) |
| Proposal prioritization within WG | WG Leads (autonomous) |
| SEP triage & closure (in scope) | WG Leads (autonomous, with documented rationale) |
| Technical design within scope | WG consensus |
| Spec changes (additive) | WG consensus → Core Maintainer approval |
| Spec changes (breaking/fundamental) | WG consensus → Core Maintainer approval + wider review |
| Scope expansion | Core Maintainer approval required |
| WG Member approval | WG Member sponsors |
Operations
| Meeting | Frequency | Duration | Purpose |
|---|---|---|---|
| Working Session | Weekly | 30 min | Technical discussion, proposal review |
Deliverables & Success Metrics
Active Work Items
| Item | Status | Target Date | Champion |
|---|---|---|---|
| SEP: Events in MCP v1 RFC | Ideating | End April | TBD |
| Reference implementation in Tier-1 SDKs | — | End April | TBD |
Success Criteria
- An accepted SEP defining the trigger/callback mechanism and its subscription lifecycle.
- Reference implementations in at least two Tier-1 SDKs.
- Conformance test coverage for the new primitives.
Changelog
| Date | Change |
|---|---|
| 2026-03-24 | Initial charter |