addressing comments

Author: tninja

README.org

@@ -225,7 +225,7 @@ These tools add:
 - =get_feature_load_state=: inspect whether an Emacs feature is loaded and where it comes from
 - =get_recent_messages=: return the latest lines from =*Messages*=
 - =get_last_error_backtrace=: return the most recently recorded Emacs command error snapshot
-- =eval_elisp=: evaluate a single Emacs Lisp form in a chosen buffer context when explicitly enabled (no restrictions once enabled)
+- =eval_elisp=: evaluate arbitrary Emacs Lisp with possible side effects in a chosen buffer context when explicitly enabled (no restrictions once enabled)
 
 The old =ai-code-mcp-editor-tools.el= module has been removed. Its live-editor read tools are now built in, while =eval_elisp= remains an explicit opt-in.
 
@@ -235,7 +235,7 @@ To register =eval_elisp=:
 (setq ai-code-mcp-debug-tools-enable-eval-elisp t)
 #+end_src
 
-Once enabled, =eval_elisp= can evaluate any Emacs Lisp form without restrictions. It takes =code= (a single top-level form), optional =buffer_name= or =file_path= for evaluation context, and optional =timeout_ms=. This is useful for letting the AI apply fixes by evaluating modified function definitions directly.
+Once enabled, =eval_elisp= can evaluate any Emacs Lisp form without restrictions. It takes =code= (a single top-level form), optional =buffer_name= or =file_path= for evaluation context, optional =capture_messages= to collect new =*Messages*= output, optional =include_backtrace= to include a backtrace on failure, and optional =timeout_ms=. This is useful for letting the AI apply fixes by evaluating modified function definitions directly.
 
 screenshot inside Codex cli:
 

ai-code-mcp-debug-tools.el

@@ -81,7 +81,7 @@
 (defconst ai-code-mcp-debug-tools--eval-spec
   '(:function ai-code-mcp-eval-elisp
     :name "eval_elisp"
-    :description "Evaluate a single Emacs Lisp form."
+    :description "Evaluate arbitrary Emacs Lisp with possible side effects once explicitly enabled."
     :args ((:name "code"
             :type string
             :description "Single Emacs Lisp form to evaluate.")
@@ -190,14 +190,16 @@
                 changed))))))
 
 (defun ai-code-mcp-debug-tools--context-summary (buffer)
-  "Return a summary of BUFFER after an evaluation."
-  (let ((position (ai-code-mcp-debug-tools--point-line-column
-                   buffer
-                   (with-current-buffer buffer (point)))))
-    `((buffer_name . ,(buffer-name buffer))
-      (file_path . ,(buffer-file-name buffer))
-      (line . ,(alist-get 'line position))
-      (column . ,(alist-get 'column position)))))
+  "Return a summary of BUFFER after an evaluation.
+Return nil when BUFFER is no longer live."
+  (when (buffer-live-p buffer)
+    (let ((position (ai-code-mcp-debug-tools--point-line-column
+                     buffer
+                     (with-current-buffer buffer (point)))))
+      `((buffer_name . ,(buffer-name buffer))
+        (file_path . ,(buffer-file-name buffer))
+        (line . ,(alist-get 'line position))
+        (column . ,(alist-get 'column position))))))
 
 (defun ai-code-mcp-debug-tools--parse-single-form (code)
   "Parse CODE and return exactly one top-level Emacs Lisp form."

test/test_ai-code-mcp-debug-tools.el

@@ -121,6 +121,21 @@
                                (alist-get 'tools tools-result))))
       (should (member "eval_elisp" tool-names)))))
 
+(ert-deftest ai-code-test-mcp-tools-list-warns-eval-elisp-is-unrestricted ()
+  "Eval tool metadata should warn about unrestricted side effects."
+  (let ((ai-code-mcp-server-tools nil)
+        (ai-code-mcp-debug-tools-enabled t)
+        (ai-code-mcp-debug-tools-enable-eval-elisp t))
+    (let* ((tools-result (ai-code-mcp-dispatch "tools/list"))
+           (eval-tool (seq-find
+                       (lambda (tool)
+                         (equal "eval_elisp" (alist-get 'name tool)))
+                       (alist-get 'tools tools-result)))
+           (description (alist-get 'description eval-tool)))
+      (should eval-tool)
+      (should (string-match-p "arbitrary Emacs Lisp" description))
+      (should (string-match-p "side effects" description)))))
+
 (ert-deftest ai-code-test-mcp-eval-elisp-uses-target-buffer ()
   "Eval should run against the requested buffer context."
   (let ((ai-code-mcp-server-tools nil)
@@ -197,6 +212,26 @@
       (when (buffer-live-p buffer)
         (kill-buffer buffer)))))
 
+(ert-deftest ai-code-test-mcp-eval-elisp-survives-killed-target-buffer ()
+  "Eval should still return JSON when the target buffer is killed."
+  (let ((ai-code-mcp-server-tools nil)
+        (ai-code-mcp-debug-tools-enabled t)
+        (ai-code-mcp-debug-tools-enable-eval-elisp t)
+        (buffer (generate-new-buffer " *ai-code-mcp-eval-kill*")))
+    (let ((payload
+           (unwind-protect
+               (ai-code-test-mcp-debug-tools--read-json-payload
+                (ai-code-mcp-dispatch
+                 "tools/call"
+                 `((name . "eval_elisp")
+                   (arguments . ((code . "(kill-buffer (current-buffer))")
+                                 (buffer_name . ,(buffer-name buffer)))))))
+             (when (buffer-live-p buffer)
+               (kill-buffer buffer)))))
+      (should (equal t (alist-get 'ok payload)))
+      (should (equal "t" (alist-get 'value_repr payload)))
+      (should-not (alist-get 'context_after payload)))))
+
 (ert-deftest ai-code-test-mcp-get-variable-value-returns-bound-variable ()
   "Variable value tool should stringify the requested Emacs variable."
   (let ((ai-code-mcp-server-tools nil)
@@ -516,6 +551,14 @@
       (when (fboundp (intern-soft func-name))
         (fmakunbound (intern func-name))))))
 
+(ert-deftest ai-code-test-readme-documents-eval-elisp-debug-options ()
+  "README should mention the eval_elisp debugging options."
+  (with-temp-buffer
+    (insert-file-contents "README.org")
+    (dolist (option '("=capture_messages=" "=include_backtrace="))
+      (goto-char (point-min))
+      (should (search-forward option nil t)))))
+
 (provide 'test_ai-code-mcp-debug-tools)
 
 ;;; test_ai-code-mcp-debug-tools.el ends here