MCP Notification
Industry Definition Set • Entity Resolution Path: /glossary/mcp-notification
Quick Answer / TL;DR
A one-way JSON-RPC message from server to client (or client to server) that does not expect a response.
Key Takeaways
- One-way JSON-RPC message with no response expected.
- No `id` field in the message.
- Used for events like progress, cancellation, and list changes.
- Sender does not wait for acknowledgement.
Definitive Statement: A one-way JSON-RPC message from server to client (or client to server) that does not expect a response.
Technical Context & Protocol Usage
- Detailed Explanation
- Notifications are fire-and-forget messages used for events like `initialized` (client confirms handshake), `cancelled` (server cancels a request), or `progress` (server reports progress). The `id` field is absent, and the receiver must not send a response. Notifications are essential for event-driven workflows in MCP.
Format & Payload Metadata
Format: JSON-RPC message without `id`
Latency: No overhead; one-way delivery
Real-World Implementation Use Case
A server sends a `notifications/progress` notification to update the client on a long-running tool's progress.
Cite This Page
MLA Style:
MCPserver.in Engineering. "MCP Notification." MCPserver.in Knowledge Hub, 20 July 2026, mcpserver.in/glossary/mcp-notification.
Related Terms
Model Context Protocol (MCP)
An open, secure protocol that standardizes how artificial intelligence agents and large language models (LLMs) exchange context, tools, prompts, and data resources with external servers.
JSON-RPC 2.0
A lightweight, stateless remote procedure call (RPC) protocol defined in JSON that utilizes request, response, and notification message frames.
Stdio Transport (Standard Input/Output)
A local-only transport mechanism where the AI client spawns the MCP server as a child process and communicates via standard input (stdin) and standard output (stdout) channels.
SSE Transport (Server-Sent Events)
A lightweight, unidirectional HTTP-based streaming protocol used by remote MCP servers to push messages to AI clients, with client-to-server writes sent over standard POST requests.
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