diff --git a/src/core/prompts/tools/native-tools/record_lesson.ts b/src/core/prompts/tools/native-tools/record_lesson.ts
new file mode 100644
index 0000000000..0c16094844
--- /dev/null
+++ b/src/core/prompts/tools/native-tools/record_lesson.ts
@@ -0,0 +1,46 @@
+import type OpenAI from "openai"
+
+/**
+ * Tool for recording lessons learned to AGENT.md (Phase 4 requirement).
+ * This tool allows the agent to append lessons learned when verification steps fail
+ * or when important insights are discovered during development.
+ */
+const recordLesson: OpenAI.Chat.ChatCompletionFunctionTool = {
+	type: "function",
+	function: {
+		name: "record_lesson",
+		description:
+			"Record a lesson learned to .orchestration/AGENT.md. Use this tool when verification steps (linter/test) fail, when architectural decisions are made, or when important insights are discovered. Lessons are appended with timestamps and context information.",
+		parameters: {
+			type: "object",
+			properties: {
+				lesson: {
+					type: "string",
+					description:
+						"The lesson learned or insight to record. Should be clear and actionable for future reference.",
+				},
+				context: {
+					type: "object",
+					properties: {
+						tool: {
+							type: "string",
+							description: "Optional: The tool that was being used when the lesson was learned.",
+						},
+						error: {
+							type: "string",
+							description: "Optional: The error message or issue that led to this lesson.",
+						},
+						file: {
+							type: "string",
+							description: "Optional: The file path related to this lesson.",
+						},
+					},
+					description: "Optional context information about when/where this lesson was learned.",
+				},
+			},
+			required: ["lesson"],
+		},
+	},
+}
+
+export default recordLesson