Fix MCP tool execution to use proper JSON-RPC 2.0 format

The /mcp/call_tool endpoint expects JSON-RPC 2.0 format requests.
Updated to send proper RPC structure and parse RPC responses.

Request format:
{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "tool_name",
    "arguments": {...}
  },
  "id": 1
}

Response parsing updated to extract result from JSON-RPC envelope:
result.result.content[0].text

This fixes the 400 validation error:
"Field required: JSONRPCRequest.method, jsonrpc, id"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

scripts/discordbot.py

@@ -99,8 +99,13 @@ async def execute_mcp_tool(tool_name: str, arguments: dict) -> str:
                 f"{base_url}/mcp/call_tool",
                 headers=headers,
                 json={
-                    "name": tool_name,
-                    "arguments": arguments
+                    "jsonrpc": "2.0",
+                    "method": "tools/call",
+                    "params": {
+                        "name": tool_name,
+                        "arguments": arguments
+                    },
+                    "id": 1
                 }
             )
 
@@ -110,12 +115,26 @@ async def execute_mcp_tool(tool_name: str, arguments: dict) -> str:
                 result = response.json()
                 debug_log(f"MCP tool result: {str(result)[:200]}...")
 
-                # MCP returns content in various formats, extract the text
+                # Handle JSON-RPC response format
                 if isinstance(result, dict):
+                    # Check for JSON-RPC result
+                    if "result" in result:
+                        rpc_result = result["result"]
+                        # MCP tool results have a "content" array
+                        if isinstance(rpc_result, dict) and "content" in rpc_result:
+                            content = rpc_result["content"]
+                            if isinstance(content, list) and len(content) > 0:
+                                # Handle text content blocks
+                                first_content = content[0]
+                                if isinstance(first_content, dict) and "text" in first_content:
+                                    return first_content["text"]
+                                return json.dumps(content)
+                            return json.dumps(content) if content else "Tool executed successfully"
+                        return json.dumps(rpc_result)
+                    # Fallback for non-RPC format
                     if "content" in result:
                         content = result["content"]
                         if isinstance(content, list) and len(content) > 0:
-                            # Handle text content blocks
                             first_content = content[0]
                             if isinstance(first_content, dict) and "text" in first_content:
                                 return first_content["text"]