Guidance on migrating from SSE to Streamable HTTP in MCP SDK C#

[maximilianosilva]

Pre-submission Checklist

• I have checked that this question would not be more appropriate as an issue in a specific repository
• I have searched existing discussions and documentation for answers

Question Category

• Protocol Specification
• SDK Usage
• Server Implementation
• General Implementation
• Documentation
• Other

Your Question

Hello,

I'm working with the MCP SDK for C# and have a question about migrating my transport from Server-Sent Events (SSE) to Streamable HTTP.

My current server-side configuration in Program.cs is:

builder.Services.AddMcpServer()
    .WithHttpTransport()
    .WithToolsFromAssembly();

This works perfectly. It exposes the http://localhost:3004/sse endpoint, and my MCP client connects to it successfully.

Now, I want to update my implementation to use the new Streamable HTTP transport. I assumed that by using the same configuration, the base endpoint (http://localhost:3004) would work for the streamable connection, but my client fails to recognize it.

Could you please clarify the following?

• Is there an additional or different configuration required on the server-side to enable Streamable HTTP instead of SSE?
• What is the correct URI that the MCP client should be pointed to for a Streamable HTTP connection?

Any examples or documentation on this transition would be greatly appreciated.

Thank you!