Triggers and Events Charter

Charter for the MCP Triggers and Events Working Group.

Group Type

Working Group

Mission 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