feat: add reminders_remove tool for single-reminder removal

- reminders_remove(index) removes one reminder by 1-based index
- reminders_list now returns numbered output (1. heading / body)
  so any model can easily identify which index to pass
- _parse_sections() / _sections_to_text() helpers for clean round-trip
- Not in CONFIRM_REQUIRED — targeted removal is safe without a gate

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/tools/__init__.py

@@ -37,6 +37,7 @@ from tools.cron import (
 from tools.reminders import (
     reminders_add as _reminders_add,
     reminders_list as _reminders_list,
+    reminders_remove as _reminders_remove,
     reminders_clear as _reminders_clear,
 )
 from tools.scratch import (
@@ -308,6 +309,7 @@ _CALLABLES: dict[str, callable] = {
     "cron_toggle": _cron_toggle,
     "reminders_add": _reminders_add,
     "reminders_list": _reminders_list,
+    "reminders_remove": _reminders_remove,
     "reminders_clear": _reminders_clear,
     "scratch_read": _scratch_read,
     "scratch_write": _scratch_write,
@@ -584,6 +586,24 @@ _reminders_list_declaration = types.FunctionDeclaration(
     parameters=types.Schema(type=types.Type.OBJECT, properties={}),
 )
 
+_reminders_remove_declaration = types.FunctionDeclaration(
+    name="reminders_remove",
+    description=(
+        "Remove a single reminder by its number. "
+        "Call reminders_list first to get the numbered list, then pass the number of the reminder to remove."
+    ),
+    parameters=types.Schema(
+        type=types.Type.OBJECT,
+        properties={
+            "index": types.Schema(
+                type=types.Type.INTEGER,
+                description="The number of the reminder to remove (1 = first item in reminders_list output).",
+            ),
+        },
+        required=["index"],
+    ),
+)
+
 _reminders_clear_declaration = types.FunctionDeclaration(
     name="reminders_clear",
     description=(
@@ -864,6 +884,7 @@ _ALL_DECLARATIONS: list[types.FunctionDeclaration] = [
     _cron_toggle_declaration,
     _reminders_add_declaration,
     _reminders_list_declaration,
+    _reminders_remove_declaration,
     _reminders_clear_declaration,
     _scratch_read_declaration,
     _scratch_write_declaration,