fix(extensions): handle empty tool responses better

Author: ravitemer

lua/mcphub/extensions/avante.lua

@@ -91,7 +91,13 @@ function M.mcp_tool()
                     },
                     callback = function(result, err)
                         --result has .text and .images [{mimeType, data}]
-                        on_complete(result.text, err)
+                        local text = result and result.text or ""
+                        if not text or text == "" then
+                            local empty_response =
+                                string.format("`%s` successfull. `%s` returned no text.", params.action, params.uri)
+                            text = empty_response
+                        end
+                        on_complete(text, err)
                     end,
                 })
             elseif params.action == "use_mcp_tool" then
@@ -105,7 +111,16 @@ function M.mcp_tool()
                         if result.error then
                             on_complete(nil, result.error)
                         else
-                            on_complete(result.text, err)
+                            local text = result and result.text or ""
+                            if not text or text == "" then
+                                local empty_response = string.format(
+                                    "`%s` successfull. `%s` returned no text.",
+                                    params.action,
+                                    params.tool_name
+                                )
+                                text = empty_response
+                            end
+                            on_complete(text, err)
                         end
                     end,
                 })

lua/mcphub/extensions/codecompanion/utils.lua

@@ -150,6 +150,7 @@ function M.create_output_handlers(action_name, has_function_calling, opts)
             local result = has_function_calling and stdout[#stdout] or cmd[#cmd]
             agent = has_function_calling and agent or self
             -- Show text content if present
+            local tool_call_result_added = false
             if result.text and result.text ~= "" then
                 local to_llm = string.format(
                     [[**`%s` Tool**: Returned the following:
@@ -161,13 +162,12 @@ function M.create_output_handlers(action_name, has_function_calling, opts)
                     result.text
                 )
                 add_tool_output(action_name, self, agent.chat, to_llm, false, has_function_calling, opts)
-            else
+                tool_call_result_added = true
+            end
+            if not tool_call_result_added then
                 -- When a tool returns no text content, still send a message to
                 -- ensure the tool_call_id protocol is satisfied
-                local to_llm = string.format(
-                    "**`%s` Tool**: Completed with no output",
-                    action_name
-                )
+                local to_llm = string.format("**`%s` Tool**: Completed with no output", action_name)
                 add_tool_output(action_name, self, agent.chat, to_llm, false, has_function_calling, opts)
             end
             -- TODO: Add image support when codecompanion supports it