diff --git a/agents-api/agents_api/models/task/create_or_update_task.py b/agents-api/agents_api/models/task/create_or_update_task.py
index af7e258d9..702e505ad 100644
--- a/agents-api/agents_api/models/task/create_or_update_task.py
+++ b/agents-api/agents_api/models/task/create_or_update_task.py
@@ -64,7 +64,7 @@ def create_or_update_task(
     data.metadata = data.metadata or {}
     data.input_schema = data.input_schema or {}
 
-    task_data = task_to_spec(data).model_dump(exclude_none=True, exclude_unset=True)
+    task_data = task_to_spec(data).model_dump(exclude_none=True, exclude_unset=True, mode="json")
     task_data.pop("task_id", None)
     task_data["created_at"] = utcnow().timestamp()
 
diff --git a/agents-api/agents_api/models/task/create_task.py b/agents-api/agents_api/models/task/create_task.py
index a44146c34..9affe0ead 100644
--- a/agents-api/agents_api/models/task/create_task.py
+++ b/agents-api/agents_api/models/task/create_task.py
@@ -55,7 +55,7 @@ def create_task(
     # Prepares the update data by filtering out None values and adding user_id and developer_id.
     columns, values = cozo_process_mutate_data(
         {
-            **task_spec.model_dump(exclude_none=True, exclude_unset=True),
+            **task_spec.model_dump(exclude_none=True, exclude_unset=True, mode="json"),
             "task_id": str(task_id),
             "agent_id": str(agent_id),
         }
diff --git a/agents-api/agents_api/routers/agents/create_agent.py b/agents-api/agents_api/routers/agents/create_agent.py
index 06e8f17cd..2e1c4df0a 100644
--- a/agents-api/agents_api/routers/agents/create_agent.py
+++ b/agents-api/agents_api/routers/agents/create_agent.py
@@ -4,13 +4,12 @@
 from fastapi import Depends
 from starlette.status import HTTP_201_CREATED
 
-from ...models.agent.create_agent import create_agent as create_agent_query
-
 from ...autogen.openapi_model import (
     CreateAgentRequest,
     ResourceCreatedResponse,
 )
 from ...dependencies.developer_id import get_developer_id
+from ...models.agent.create_agent import create_agent as create_agent_query
 from .router import router
 
 
diff --git a/agents-api/tests/test_execution_workflow.py b/agents-api/tests/test_execution_workflow.py
index b6394f1bc..42ca4cd78 100644
--- a/agents-api/tests/test_execution_workflow.py
+++ b/agents-api/tests/test_execution_workflow.py
@@ -441,6 +441,63 @@ async def _(
             assert result["hello"] == data.input["test"]
 
 
+@test("workflow: tool call api_call")
+async def _(
+    client=cozo_client,
+    developer_id=test_developer_id,
+    agent=test_agent,
+):
+    data = CreateExecutionRequest(input={"test": "input"})
+
+    task = create_task(
+        developer_id=developer_id,
+        agent_id=agent.id,
+        data=CreateTaskRequest(
+            **{
+                "name": "test task",
+                "description": "test task about",
+                "input_schema": {"type": "object", "additionalProperties": True},
+                "tools": [
+                    {
+                        "type": "api_call",
+                        "name": "hello",
+                        "api_call": {
+                            "method": "GET",
+                            "url": "https://httpbin.org/get",
+                        },
+                    }
+                ],
+                "main": [
+                    {
+                        "tool": "hello",
+                        "params": {"test": "_.test"},
+                    },
+                    {
+                        "evaluate": {"hello": "_.json()['args']['test']"},
+                    }
+                ],
+            }
+        ),
+        client=client,
+    )
+
+    async with patch_testing_temporal() as (_, mock_run_task_execution_workflow):
+        execution, handle = await start_execution(
+            developer_id=developer_id,
+            task_id=task.id,
+            data=data,
+            client=client,
+        )
+
+        assert handle is not None
+        assert execution.task_id == task.id
+        assert execution.input == data.input
+        mock_run_task_execution_workflow.assert_called_once()
+
+        result = await handle.result()
+        assert result["hello"] == data.input["test"]
+
+
 @test("workflow: tool call integration dummy")
 async def _(
     client=cozo_client,