How to read the Mcp-Session-Id from the tool.

[kaniosm]

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

Some of my tools are session dependent, how can I read the Mcp-Session-Id when the tool get executed?

[kaniosm]

managed to get the "Mcp-Session-Id" from the request headers usign IHttpContextAccessor accessor.
Had to add builder.Services.AddHttpContextAccessor();

[jph33]

Hi. Can you provide an example of how you achieved to get the mcp-session-id during tool exection please?

[kaniosm]

Hi, you can find an example below...

For this to work, you have register HttpContextAccessor in your startup:
builder.Services.AddHttpContextAccessor();

and use the sse client not the streamable http client ... or configure streamable http to be stateless:

builder.Services.AddMcpServer() .WithHttpTransport(opt => { opt.Stateless = true;
or configure httptrnasport with PerSessionExecutionContext:

builder.Services.AddMcpServer() .WithHttpTransport(opt => { opt.PerSessionExecutionContext = true;

[McpServerTool(Name = "TestTool"), Description("This function is ...")] public static async Task<string> TestTool(IHttpContextAccessor httpContextAccessor) { if (httpContextAccessor.HttpContext.Request.Headers.TryGetValue("My-Session-Id", out var sessionId)) { .... } return "Ok"; }

[jph33]

Thank you very much @kaniosm
I make it work with http stateful.
I added:
builder.Services.AddHttpContextAccessor();
And in the constructor of the tool call i added :

  public MyTools(IHttpContextAccessor httpContextAccessor)
  {
    this._httpContext = httpContextAccessor.HttpContext;
  }

And in each tool i use this._httpContext to get the request headers

[kaniosm]

Glad I could help!