MCP Client uses REST endpoints instead of JSON-RPC as required by MCP spec

[bobtista]

I noticed that the current MCPClient implementation uses RESTful endpoints (e.g., GET /tools, POST /tools/{tool_name}) to interact with the MCP server. However, according to the MCP specification, MCP is designed to use JSON-RPC over HTTP/SSE, not REST.

eg to list tools, something like

{
    "jsonrpc": "2.0",
    "method": "tools/list",
    "params": {},
    "id": 1
}

to call a tool, something like

{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "git_status",
      "arguments": {}
    },
    "id": 2
  }

This results in 404 errors when connecting to MCP servers that support SSE.

Steps to reproduce:
Run an MCP server that implements the JSON-RPC protocol
Attempt to use the current MCPClient to list tools or call a tool - eg set
Observe 404 errors and no JSON-RPC traffic.

[Emilmeister]

Same problem. Cannot connect A2AServer from google/A2A and A2AClient from this framework

[themanojdesai]

This issue has been fixed in 0.5.6, kindly check and close this @bobtista @Emilmeister

[bobtista]

This issue has been fixed in 0.5.6, kindly check and close this @bobtista @Emilmeister

I haven't tested it locally, but this LGTM

[themanojdesai]

If looks good then could you please close the issue ?

Thanks @bobtista !