diff --git a/mlf-codegen/src/lib.rs b/mlf-codegen/src/lib.rs
index 192e5e9..6c2aff8 100644
--- a/mlf-codegen/src/lib.rs
+++ b/mlf-codegen/src/lib.rs
@@ -586,7 +586,14 @@ fn generate_subscription_json(
 }
 
 fn generate_def_type_json(def_type: &DefType, usage_counts: &HashMap<String, usize>, workspace: &Workspace, current_namespace: &str) -> Value {
-    generate_type_json(&def_type.ty, usage_counts, workspace, current_namespace)
+    let mut field_json = generate_type_json(&def_type.ty, usage_counts, workspace, current_namespace);
+    // Add description if the type definition has doc comments
+    if !def_type.docs.is_empty() {
+        if let Some(obj) = field_json.as_object_mut() {
+            obj.shift_insert(1, "description".to_string(), json!(extract_docs(&def_type.docs)));
+        }
+    }
+    field_json
 }
 
 fn generate_type_json(ty: &Type, usage_counts: &HashMap<String, usize>, workspace: &Workspace, current_namespace: &str) -> Value {
diff --git a/tests/codegen/lexicon/doc_comments/expected.json b/tests/codegen/lexicon/doc_comments/expected.json
new file mode 100644
index 0000000..676c8c4
--- /dev/null
+++ b/tests/codegen/lexicon/doc_comments/expected.json
@@ -0,0 +1,30 @@
+{
+  "$type": "com.atproto.lexicon.schema",
+  "lexicon": 1,
+  "id": "com.example.thread",
+  "defs": {
+    "main": {
+      "type": "record",
+      "description": "A forum thread",
+      "key": "tid",
+      "record": {
+        "type": "object",
+        "required": [
+          "title"
+        ],
+        "properties": {
+          "title": {
+            "type": "ref",
+            "ref": "#title"
+          }
+        }
+      }
+    },
+    "title": {
+      "type": "string",
+      "description": "Thread title",
+      "maxLength": 200,
+      "minLength": 1
+    }
+  }
+}
diff --git a/tests/codegen/lexicon/doc_comments/input.mlf b/tests/codegen/lexicon/doc_comments/input.mlf
new file mode 100644
index 0000000..8ca195b
--- /dev/null
+++ b/tests/codegen/lexicon/doc_comments/input.mlf
@@ -0,0 +1,10 @@
+/// A forum thread
+record thread {
+    title!: title,
+}
+
+/// Thread title
+def type title = string constrained {
+    maxLength: 200,
+    minLength: 1,
+};
diff --git a/tests/codegen/lexicon/doc_comments/test.toml b/tests/codegen/lexicon/doc_comments/test.toml
new file mode 100644
index 0000000..68ec5ce
--- /dev/null
+++ b/tests/codegen/lexicon/doc_comments/test.toml
@@ -0,0 +1,4 @@
+[test]
+name = "doc_comments"
+description = "Test doc comments for defs"
+namespace = "com.example.thread"