feat(mcp): Add list_prompts, get_prompt methods (#160)

Co-authored-by: ketan-clairyon <[email protected]>
Co-authored-by: Dean Schmigelski <[email protected]>

Author: 3 people

src/strands/tools/mcp/mcp_client.py

@@ -20,6 +20,7 @@
 
 from mcp import ClientSession, ListToolsResult
 from mcp.types import CallToolResult as MCPCallToolResult
+from mcp.types import GetPromptResult, ListPromptsResult
 from mcp.types import ImageContent as MCPImageContent
 from mcp.types import TextContent as MCPTextContent
 
@@ -165,6 +166,54 @@ async def _list_tools_async() -> ListToolsResult:
         self._log_debug_with_thread("successfully adapted %d MCP tools", len(mcp_tools))
         return PaginatedList[MCPAgentTool](mcp_tools, token=list_tools_response.nextCursor)
 
+    def list_prompts_sync(self, pagination_token: Optional[str] = None) -> ListPromptsResult:
+        """Synchronously retrieves the list of available prompts from the MCP server.
+
+        This method calls the asynchronous list_prompts method on the MCP session
+        and returns the raw ListPromptsResult with pagination support.
+
+        Args:
+            pagination_token: Optional token for pagination
+
+        Returns:
+            ListPromptsResult: The raw MCP response containing prompts and pagination info
+        """
+        self._log_debug_with_thread("listing MCP prompts synchronously")
+        if not self._is_session_active():
+            raise MCPClientInitializationError(CLIENT_SESSION_NOT_RUNNING_ERROR_MESSAGE)
+
+        async def _list_prompts_async() -> ListPromptsResult:
+            return await self._background_thread_session.list_prompts(cursor=pagination_token)
+
+        list_prompts_result: ListPromptsResult = self._invoke_on_background_thread(_list_prompts_async()).result()
+        self._log_debug_with_thread("received %d prompts from MCP server", len(list_prompts_result.prompts))
+        for prompt in list_prompts_result.prompts:
+            self._log_debug_with_thread(prompt.name)
+
+        return list_prompts_result
+
+    def get_prompt_sync(self, prompt_id: str, args: dict[str, Any]) -> GetPromptResult:
+        """Synchronously retrieves a prompt from the MCP server.
+
+        Args:
+            prompt_id: The ID of the prompt to retrieve
+            args: Optional arguments to pass to the prompt
+
+        Returns:
+            GetPromptResult: The prompt response from the MCP server
+        """
+        self._log_debug_with_thread("getting MCP prompt synchronously")
+        if not self._is_session_active():
+            raise MCPClientInitializationError(CLIENT_SESSION_NOT_RUNNING_ERROR_MESSAGE)
+
+        async def _get_prompt_async() -> GetPromptResult:
+            return await self._background_thread_session.get_prompt(prompt_id, arguments=args)
+
+        get_prompt_result: GetPromptResult = self._invoke_on_background_thread(_get_prompt_async()).result()
+        self._log_debug_with_thread("received prompt from MCP server")
+
+        return get_prompt_result
+
     def call_tool_sync(
         self,
         tool_use_id: str,

tests/strands/tools/mcp/test_mcp_client.py

@@ -4,6 +4,7 @@
 import pytest
 from mcp import ListToolsResult
 from mcp.types import CallToolResult as MCPCallToolResult
+from mcp.types import GetPromptResult, ListPromptsResult, Prompt, PromptMessage
 from mcp.types import TextContent as MCPTextContent
 from mcp.types import Tool as MCPTool
 
@@ -404,3 +405,64 @@ def test_exception_when_future_not_running():
 
         # Verify that set_exception was not called since the future was not running
         mock_future.set_exception.assert_not_called()
+
+
+# Prompt Tests - Sync Methods
+
+
+def test_list_prompts_sync(mock_transport, mock_session):
+    """Test that list_prompts_sync correctly retrieves prompts."""
+    mock_prompt = Prompt(name="test_prompt", description="A test prompt", id="prompt_1")
+    mock_session.list_prompts.return_value = ListPromptsResult(prompts=[mock_prompt])
+
+    with MCPClient(mock_transport["transport_callable"]) as client:
+        result = client.list_prompts_sync()
+
+        mock_session.list_prompts.assert_called_once_with(cursor=None)
+        assert len(result.prompts) == 1
+        assert result.prompts[0].name == "test_prompt"
+        assert result.nextCursor is None
+
+
+def test_list_prompts_sync_with_pagination_token(mock_transport, mock_session):
+    """Test that list_prompts_sync correctly passes pagination token and returns next cursor."""
+    mock_prompt = Prompt(name="test_prompt", description="A test prompt", id="prompt_1")
+    mock_session.list_prompts.return_value = ListPromptsResult(prompts=[mock_prompt], nextCursor="next_page_token")
+
+    with MCPClient(mock_transport["transport_callable"]) as client:
+        result = client.list_prompts_sync(pagination_token="current_page_token")
+
+        mock_session.list_prompts.assert_called_once_with(cursor="current_page_token")
+        assert len(result.prompts) == 1
+        assert result.prompts[0].name == "test_prompt"
+        assert result.nextCursor == "next_page_token"
+
+
+def test_list_prompts_sync_session_not_active():
+    """Test that list_prompts_sync raises an error when session is not active."""
+    client = MCPClient(MagicMock())
+
+    with pytest.raises(MCPClientInitializationError, match="client session is not running"):
+        client.list_prompts_sync()
+
+
+def test_get_prompt_sync(mock_transport, mock_session):
+    """Test that get_prompt_sync correctly retrieves a prompt."""
+    mock_message = PromptMessage(role="user", content=MCPTextContent(type="text", text="This is a test prompt"))
+    mock_session.get_prompt.return_value = GetPromptResult(messages=[mock_message])
+
+    with MCPClient(mock_transport["transport_callable"]) as client:
+        result = client.get_prompt_sync("test_prompt_id", {"key": "value"})
+
+        mock_session.get_prompt.assert_called_once_with("test_prompt_id", arguments={"key": "value"})
+        assert len(result.messages) == 1
+        assert result.messages[0].role == "user"
+        assert result.messages[0].content.text == "This is a test prompt"
+
+
+def test_get_prompt_sync_session_not_active():
+    """Test that get_prompt_sync raises an error when session is not active."""
+    client = MCPClient(MagicMock())
+
+    with pytest.raises(MCPClientInitializationError, match="client session is not running"):
+        client.get_prompt_sync("test_prompt_id", {})

tests_integ/test_mcp_client.py

@@ -18,18 +18,17 @@
 from strands.types.tools import ToolUse
 
 
-def start_calculator_server(transport: Literal["sse", "streamable-http"], port=int):
+def start_comprehensive_mcp_server(transport: Literal["sse", "streamable-http"], port=int):
     """
-    Initialize and start an MCP calculator server for integration testing.
+    Initialize and start a comprehensive MCP server for integration testing.
 
-    This function creates a FastMCP server instance that provides a simple
-    calculator tool for performing addition operations. The server uses
-    Server-Sent Events (SSE) transport for communication, making it accessible
-    over HTTP.
+    This function creates a FastMCP server instance that provides tools, prompts,
+    and resources all in one server for comprehensive testing. The server uses
+    Server-Sent Events (SSE) or streamable HTTP transport for communication.
     """
     from mcp.server import FastMCP
 
-    mcp = FastMCP("Calculator Server", port=port)
+    mcp = FastMCP("Comprehensive MCP Server", port=port)
 
     @mcp.tool(description="Calculator tool which performs calculations")
     def calculator(x: int, y: int) -> int:
@@ -44,6 +43,15 @@ def generate_custom_image() -> MCPImageContent:
         except Exception as e:
             print("Error while generating custom image: {}".format(e))
 
+    # Prompts
+    @mcp.prompt(description="A greeting prompt template")
+    def greeting_prompt(name: str = "World") -> str:
+        return f"Hello, {name}! How are you today?"
+
+    @mcp.prompt(description="A math problem prompt template")
+    def math_prompt(operation: str = "addition", difficulty: str = "easy") -> str:
+        return f"Create a {difficulty} {operation} math problem and solve it step by step."
+
     mcp.run(transport=transport)
 
 
@@ -58,8 +66,9 @@ def test_mcp_client():
     {'role': 'assistant', 'content': [{'text': '\n\nThe result of adding 1 and 2 is 3.'}]}
     """  # noqa: E501
 
+    # Start comprehensive server with tools, prompts, and resources
     server_thread = threading.Thread(
-        target=start_calculator_server, kwargs={"transport": "sse", "port": 8000}, daemon=True
+        target=start_comprehensive_mcp_server, kwargs={"transport": "sse", "port": 8000}, daemon=True
     )
     server_thread.start()
     time.sleep(2)  # wait for server to startup completely
@@ -68,8 +77,14 @@ def test_mcp_client():
     stdio_mcp_client = MCPClient(
         lambda: stdio_client(StdioServerParameters(command="python", args=["tests_integ/echo_server.py"]))
     )
+
     with sse_mcp_client, stdio_mcp_client:
-        agent = Agent(tools=sse_mcp_client.list_tools_sync() + stdio_mcp_client.list_tools_sync())
+        # Test Tools functionality
+        sse_tools = sse_mcp_client.list_tools_sync()
+        stdio_tools = stdio_mcp_client.list_tools_sync()
+        all_tools = sse_tools + stdio_tools
+
+        agent = Agent(tools=all_tools)
         agent("add 1 and 2, then echo the result back to me")
 
         tool_use_content_blocks = _messages_to_content_blocks(agent.messages)
@@ -88,6 +103,43 @@ def test_mcp_client():
             ]
         )
 
+        # Test Prompts functionality
+        prompts_result = sse_mcp_client.list_prompts_sync()
+        assert len(prompts_result.prompts) >= 2  # We expect at least greeting and math prompts
+
+        prompt_names = [prompt.name for prompt in prompts_result.prompts]
+        assert "greeting_prompt" in prompt_names
+        assert "math_prompt" in prompt_names
+
+        # Test get_prompt_sync with greeting prompt
+        greeting_result = sse_mcp_client.get_prompt_sync("greeting_prompt", {"name": "Alice"})
+        assert len(greeting_result.messages) > 0
+        prompt_text = greeting_result.messages[0].content.text
+        assert "Hello, Alice!" in prompt_text
+        assert "How are you today?" in prompt_text
+
+        # Test get_prompt_sync with math prompt
+        math_result = sse_mcp_client.get_prompt_sync(
+            "math_prompt", {"operation": "multiplication", "difficulty": "medium"}
+        )
+        assert len(math_result.messages) > 0
+        math_text = math_result.messages[0].content.text
+        assert "multiplication" in math_text
+        assert "medium" in math_text
+        assert "step by step" in math_text
+
+        # Test pagination support for prompts
+        prompts_with_token = sse_mcp_client.list_prompts_sync(pagination_token=None)
+        assert len(prompts_with_token.prompts) >= 0
+
+        # Test pagination support for tools (existing functionality)
+        tools_with_token = sse_mcp_client.list_tools_sync(pagination_token=None)
+        assert len(tools_with_token) >= 0
+
+        # TODO: Add resources testing when resources are implemented
+        # resources_result = sse_mcp_client.list_resources_sync()
+        # assert len(resources_result.resources) >= 0
+
         tool_use_id = "test-structured-content-123"
         result = stdio_mcp_client.call_tool_sync(
             tool_use_id=tool_use_id,
@@ -185,8 +237,9 @@ def test_mcp_client_without_structured_content():
     reason="streamable transport is failing in GitHub actions, debugging if linux compatibility issue",
 )
 def test_streamable_http_mcp_client():
+    """Test comprehensive MCP client with streamable HTTP transport."""
     server_thread = threading.Thread(
-        target=start_calculator_server, kwargs={"transport": "streamable-http", "port": 8001}, daemon=True
+        target=start_comprehensive_mcp_server, kwargs={"transport": "streamable-http", "port": 8001}, daemon=True
     )
     server_thread.start()
     time.sleep(2)  # wait for server to startup completely
@@ -196,12 +249,22 @@ def transport_callback() -> MCPTransport:
 
     streamable_http_client = MCPClient(transport_callback)
     with streamable_http_client:
+        # Test tools
         agent = Agent(tools=streamable_http_client.list_tools_sync())
         agent("add 1 and 2 using a calculator")
 
         tool_use_content_blocks = _messages_to_content_blocks(agent.messages)
         assert any([block["name"] == "calculator" for block in tool_use_content_blocks])
 
+        # Test prompts
+        prompts_result = streamable_http_client.list_prompts_sync()
+        assert len(prompts_result.prompts) >= 2
+
+        greeting_result = streamable_http_client.get_prompt_sync("greeting_prompt", {"name": "Charlie"})
+        assert len(greeting_result.messages) > 0
+        prompt_text = greeting_result.messages[0].content.text
+        assert "Hello, Charlie!" in prompt_text
+
 
 def _messages_to_content_blocks(messages: List[Message]) -> List[ToolUse]:
     return [block["toolUse"] for message in messages for block in message["content"] if "toolUse" in block]