feat: Add items and title to ToolParameter/ToolParamDefinition (#3003)

# What does this PR do?
<!-- Provide a short summary of what this PR does and why. Link to
relevant issues if applicable. -->
Add items and title to ToolParameter/ToolParamDefinition. Adding items
will resolve the issue that occurs with Gemini LLM when an MCP tool has
array-type properties.

<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->

## Test Plan
<!-- Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.* -->
Unite test cases will be added.

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Kai Wu <kaiwu@meta.com>
Co-authored-by: Ashwin Bharambe <ashwin.bharambe@gmail.com>

tests/unit/providers/agent/test_meta_reference_agent.py

@@ -16,9 +16,11 @@ from llama_stack.apis.agents import (
 )
 from llama_stack.apis.common.responses import PaginatedResponse
 from llama_stack.apis.inference import Inference
+from llama_stack.apis.resource import ResourceType
 from llama_stack.apis.safety import Safety
-from llama_stack.apis.tools import ToolGroups, ToolRuntime
+from llama_stack.apis.tools import ListToolsResponse, Tool, ToolGroups, ToolParameter, ToolRuntime
 from llama_stack.apis.vector_io import VectorIO
+from llama_stack.providers.inline.agents.meta_reference.agent_instance import ChatAgent
 from llama_stack.providers.inline.agents.meta_reference.agents import MetaReferenceAgentsImpl
 from llama_stack.providers.inline.agents.meta_reference.config import MetaReferenceAgentsImplConfig
 from llama_stack.providers.inline.agents.meta_reference.persistence import AgentInfo
@@ -75,11 +77,11 @@ def sample_agent_config():
         },
         input_shields=["string"],
         output_shields=["string"],
-        toolgroups=["string"],
+        toolgroups=["mcp::my_mcp_server"],
         client_tools=[
             {
-                "name": "string",
-                "description": "string",
+                "name": "client_tool",
+                "description": "Client Tool",
                 "parameters": [
                     {
                         "name": "string",
@@ -226,3 +228,83 @@ async def test_delete_agent(agents_impl, sample_agent_config):
     # Verify the agent was deleted
     with pytest.raises(ValueError):
         await agents_impl.get_agent(agent_id)
+
+
+async def test__initialize_tools(agents_impl, sample_agent_config):
+    # Mock tool_groups_api.list_tools()
+    agents_impl.tool_groups_api.list_tools.return_value = ListToolsResponse(
+        data=[
+            Tool(
+                identifier="story_maker",
+                provider_id="model-context-protocol",
+                type=ResourceType.tool,
+                toolgroup_id="mcp::my_mcp_server",
+                description="Make a story",
+                parameters=[
+                    ToolParameter(
+                        name="story_title",
+                        parameter_type="string",
+                        description="Title of the story",
+                        required=True,
+                        title="Story Title",
+                    ),
+                    ToolParameter(
+                        name="input_words",
+                        parameter_type="array",
+                        description="Input words",
+                        required=False,
+                        items={"type": "string"},
+                        title="Input Words",
+                        default=[],
+                    ),
+                ],
+            )
+        ]
+    )
+
+    create_response = await agents_impl.create_agent(sample_agent_config)
+    agent_id = create_response.agent_id
+
+    # Get an instance of ChatAgent
+    chat_agent = await agents_impl._get_agent_impl(agent_id)
+    assert chat_agent is not None
+    assert isinstance(chat_agent, ChatAgent)
+
+    # Initialize tool definitions
+    await chat_agent._initialize_tools()
+    assert len(chat_agent.tool_defs) == 2
+
+    # Verify the first tool, which is a client tool
+    first_tool = chat_agent.tool_defs[0]
+    assert first_tool.tool_name == "client_tool"
+    assert first_tool.description == "Client Tool"
+
+    # Verify the second tool, which is an MCP tool that has an array-type property
+    second_tool = chat_agent.tool_defs[1]
+    assert second_tool.tool_name == "story_maker"
+    assert second_tool.description == "Make a story"
+
+    parameters = second_tool.parameters
+    assert len(parameters) == 2
+
+    # Verify a string property
+    story_title = parameters.get("story_title")
+    assert story_title is not None
+    assert story_title.param_type == "string"
+    assert story_title.description == "Title of the story"
+    assert story_title.required
+    assert story_title.items is None
+    assert story_title.title == "Story Title"
+    assert story_title.default is None
+
+    # Verify an array property
+    input_words = parameters.get("input_words")
+    assert input_words is not None
+    assert input_words.param_type == "array"
+    assert input_words.description == "Input words"
+    assert not input_words.required
+    assert input_words.items is not None
+    assert len(input_words.items) == 1
+    assert input_words.items.get("type") == "string"
+    assert input_words.title == "Input Words"
+    assert input_words.default == []