fix(mcp): make list page cap a plain constant and use a real ListToolsResult in the unit mock

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/constants.py

@@ -136,7 +136,7 @@ MCP_CLIENT_TIMEOUT: Final = float(os.getenv("LITELLM_MCP_CLIENT_TIMEOUT", "60.0"
 MCP_TOOL_LISTING_TIMEOUT: Final = float(os.getenv("LITELLM_MCP_TOOL_LISTING_TIMEOUT", "30.0"))
 MCP_METADATA_TIMEOUT: Final = float(os.getenv("LITELLM_MCP_METADATA_TIMEOUT", "10.0"))
 MCP_HEALTH_CHECK_TIMEOUT: Final = float(os.getenv("LITELLM_MCP_HEALTH_CHECK_TIMEOUT", "10.0"))
-MCP_LIST_MAX_PAGES: Final = int(os.getenv("LITELLM_MCP_LIST_MAX_PAGES", "100"))
+MCP_LIST_MAX_PAGES: Final = 100
 
 # Allowlist of commands permitted for MCP stdio transport.
 # Prevents arbitrary command execution via /mcp-rest/test/* endpoints or server creation.

litellm/experimental_mcp_client/pagination.py

@@ -42,7 +42,7 @@ async def collect_pages(
         return items
     if pages_read >= MCP_LIST_MAX_PAGES:
         verbose_logger.warning(
-            "MCP %s from %s still paginating after %s pages (LITELLM_MCP_LIST_MAX_PAGES); returning what was read",
+            "MCP %s from %s still paginating after %s pages (MCP_LIST_MAX_PAGES); returning what was read",
             method,
             server,
             pages_read,

tests/mcp_tests/test_mcp_client_unit.py

@@ -11,7 +11,7 @@ from unittest.mock import AsyncMock, MagicMock, patch, ANY
 import litellm.experimental_mcp_client.client as mcp_client_module
 from litellm.experimental_mcp_client.client import MCPClient
 from litellm.types.mcp import MCPAuth, MCPTransport
-from mcp.types import Tool as MCPTool, CallToolResult as MCPCallToolResult
+from mcp.types import Tool as MCPTool, CallToolResult as MCPCallToolResult, ListToolsResult
 
 
 def test_mcp_client_uses_configurable_default_timeout():
@@ -174,9 +174,7 @@ class TestMCPClientUnitTests:
                 },
             )
         ]
-        mock_result = MagicMock()
-        mock_result.tools = mock_tools
-        mock_session_instance.list_tools.return_value = mock_result
+        mock_session_instance.list_tools.return_value = ListToolsResult(tools=mock_tools)
 
         client = MCPClient("http://example.com")
         result = await client.list_tools()

tests/test_litellm/experimental_mcp_client/test_pagination.py

@@ -79,4 +79,4 @@ async def test_collect_pages_honors_the_page_cap(monkeypatch, caplog):
 
     assert len(upstream.cursors_seen) == 3
     assert len(tools) == 30
-    assert any("LITELLM_MCP_LIST_MAX_PAGES" in record.getMessage() for record in caplog.records)
+    assert any("MCP_LIST_MAX_PAGES" in record.getMessage() for record in caplog.records)