jlowin
client send msg to server
Enhancement Description
Hello, server could use logging/sampling to send msg to client. How do client send general msg back to server?
Use Case
No response
Proposed Implementation
hi @merlinarer - can you elaborate on what exactly you're looking for functionality / DX wise?
Yes. I want to find a way to exchange general msg between client and server. The logging only supports to send msg to client like this:
Server.py
# Add an addition tool
@mcp.tool(
"add",
"adds two numbers"
)
async def add(a: int, b: int, ctx: Context) -> int:
"""Add two numbers"""
response = await ctx.info("Starting")
return a + b
Is there a way to support client send general msg back to server like ctx.msg? The server acts differently according to the response from client. A demo case could be like this:
@mcp.tool(
"add",
"adds two numbers or delta of two numbers"
)
async def add_or_delta(a: int, b: int, ctx: Context) -> int:
"""Add two numbers"""
await ctx.info("Starting")
response = await ctx.msg("Copy that?")
if response is "ok":
return a + b
else:
return a - b
Just wanted to chime in! For now, the MCP spec only defines a small number of notifications that the client can send:
export type ClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification;
Right now in FastMCP, you can send a progress notification and a roots list changed notification (the low-level server handles initialized notifications). Unfortunately, the spec doesn’t provide a way for clients to send a “general message notification” to the server.
It’s a good idea though! If you think this would be useful, consider opening an issue or discussion on the Model Context Protocol repo to propose expanding the spec.
