MCP Event Subscriptions

An experimental, portable subscription record for MCP Events, with an optional JWE encrypted envelope.

Store the same record in a database, a key-value store, or an upstream webhook configuration. This repository defines its fields, encrypted encoding, and validation rules, with a Python reference implementation and conformance vectors.

Independent proposal. This is not an adopted MCP specification or an IETF RFC. The format may change before a stable release. It does not change MCP event requests or notification payloads.

What is here

• Record specification and JSON Schema.
• Encrypted envelope profile: JWE Compact, dir + A256GCM, with explicit server/tenant/resource binding.
• Appwrite webhook profile: proposed storage mapping and the limits of write-only upstream state.
• Examples and conformance vectors.
• Python reference implementation.
• Upstream discussion draft.

Install the alpha release

Available on PyPI for Python 3.12 or newer:

pip install mcp-event-subscriptions==0.1.0a1

See RELEASING.md for the Trusted Publishing setup and release process.

Quick start

Python 3.12 or newer and uv:

uv sync --group dev
uv run python examples/roundtrip.py
uv run python -m unittest discover -s tests -v

import json
import secrets
from mcp_event_subscriptions import seal, open_envelope

record = json.load(open("examples/subscription.json"))
context = {
    "server": "https://mcp.example.com",
    "tenant": "project_demo",
    "resource": record["id"],
}
keys = {"k1": secrets.token_bytes(32)}
token = seal(record, keys, active_key="k1", context=context)
restored = open_envelope(token, keys, expected_context=context)
assert restored == record

The sample subscription expires in 2030. Examples and vectors use synthetic principals and secrets. Fixed test-vector keys are public fixtures, never production keys.

Scope

Version 1 describes webhook and push subscription state and optional encrypted storage. It does not specify a SQL layout, implement a delivery queue, establish current caller authorization, or make refresh/delete operations atomic. Adapters must provide their own coordination and revocation checks. Encryption cannot detect replay of an older, still-valid envelope without current state.

The Appwrite profile is documentation, not a working Appwrite adapter. It is not wire-compatible with the existing v1.<kid>.<ciphertext> envelope in appwrite/mcp PR #132.

Discussing the proposal

Start with the open questions: which fields should be common, whether an encrypted profile belongs alongside the schema, and what lifecycle guarantees adapters must expose. No proposal has been submitted upstream by this repository.

Development

uv run --group dev ruff check .
uv run --group dev black --check .
uv run python -m unittest discover -s tests -v
uv build

Licensed under the MIT License. See SECURITY.md before using the reference implementation with real secrets.