diff --git a/agents/core-logic/agent.py b/agents/core-logic/agent.py
index daa019f..fdee84a 100644
--- a/agents/core-logic/agent.py
+++ b/agents/core-logic/agent.py
@@ -9,6 +9,7 @@ import os
 import logging
 import uuid
 import httpx
+import json
 import google.auth
 import google.auth.transport.requests
 from typing import Literal
@@ -93,15 +94,26 @@ def _mcp_headers() -> dict:
     }
 
 
+import json
+...
 def _call_tool(tool: str, params: dict = None) -> dict:
+    req_id = str(uuid.uuid4())
     resp = httpx.post(
-        f"{_OPAX_MCP_URL}/tools/call",
+        f"{_OPAX_MCP_URL}/",
         headers=_mcp_headers(),
-        json={"tool": tool, "params": params or {}},
+        json={
+            "jsonrpc": "2.0",
+            "id": req_id,
+            "method": "tools/call",
+            "params": {"name": tool, "arguments": params or {}},
+        },
         timeout=30,
     )
     resp.raise_for_status()
-    return resp.json()
+    rpc_resp = resp.json()
+    if "error" in rpc_resp:
+        raise Exception(f"Tool call error: {rpc_resp['error']}")
+    return json.loads(rpc_resp["result"]["content"][0]["text"])
 
 
 def get_billing_summary() -> dict:
diff --git a/agents/core-logic/root_agent.py b/agents/core-logic/root_agent.py
index a81b9f1..b475097 100644
--- a/agents/core-logic/root_agent.py
+++ b/agents/core-logic/root_agent.py
@@ -9,6 +9,7 @@ import os
 import logging
 import uuid
 import httpx
+import json
 import google.auth
 import google.auth.transport.requests
 from typing import Literal
@@ -73,10 +74,26 @@ def _identity_token() -> str:
 def _mcp_headers() -> dict:
     return {"Authorization": f"Bearer {_identity_token()}", "X-MCP-Secret": _MCP_SECRET, "Content-Type": "application/json"}
 
+import json
+...
 def _call_tool(tool: str, params: dict = None) -> dict:
-    resp = httpx.post(f"{_OPAX_MCP_URL}/tools/call", headers=_mcp_headers(), json={"tool": tool, "params": params or {}}, timeout=30)
+    req_id = str(uuid.uuid4())
+    resp = httpx.post(
+        f"{_OPAX_MCP_URL}/",
+        headers=_mcp_headers(),
+        json={
+            "jsonrpc": "2.0",
+            "id": req_id,
+            "method": "tools/call",
+            "params": {"name": tool, "arguments": params or {}},
+        },
+        timeout=30,
+    )
     resp.raise_for_status()
-    return resp.json()
+    rpc_resp = resp.json()
+    if "error" in rpc_resp:
+        raise Exception(f"Tool call error: {rpc_resp['error']}")
+    return json.loads(rpc_resp["result"]["content"][0]["text"])
 
 def get_billing_summary() -> dict:
     """Hent billing-oversikt for OSVauco (GCP-kostnader, token-forbruk)."""