diff --git a/api/aqua-api/.js/src/main/scala/api/types/InputTypes.scala b/api/aqua-api/.js/src/main/scala/api/types/InputTypes.scala
index 7d892f836..381541f0d 100644
--- a/api/aqua-api/.js/src/main/scala/api/types/InputTypes.scala
+++ b/api/aqua-api/.js/src/main/scala/api/types/InputTypes.scala
@@ -4,7 +4,7 @@ import aqua.api.AquaAPIConfig
 import aqua.api.TargetType.*
 import aqua.js.{FunctionDefJs, ServiceDefJs}
 import aqua.model.transform.TransformConfig
-import cats.data.Validated.{invalidNec, validNec, Invalid, Valid}
+import cats.data.Validated.{invalidNec, validNec}
 import cats.data.{Chain, NonEmptyChain, Validated, ValidatedNec}
 
 import scala.scalajs.js
diff --git a/model/inline/src/main/scala/aqua/model/inline/raw/CallArrowRawInliner.scala b/model/inline/src/main/scala/aqua/model/inline/raw/CallArrowRawInliner.scala
index b3a4a4735..0007bd190 100644
--- a/model/inline/src/main/scala/aqua/model/inline/raw/CallArrowRawInliner.scala
+++ b/model/inline/src/main/scala/aqua/model/inline/raw/CallArrowRawInliner.scala
@@ -60,6 +60,7 @@ object CallArrowRawInliner extends RawInliner[CallArrowRaw] with Logging {
           vars -> Inline(
             ListMap.empty,
             Chain.one(
+              // Leave meta information in tree after inlining
               MetaModel
                 .CallArrowModel(fn.funcName)
                 .wrap(
diff --git a/model/inline/src/test/scala/aqua/model/inline/ArrowInlinerSpec.scala b/model/inline/src/test/scala/aqua/model/inline/ArrowInlinerSpec.scala
index 323d3bab5..2ca4f0388 100644
--- a/model/inline/src/test/scala/aqua/model/inline/ArrowInlinerSpec.scala
+++ b/model/inline/src/test/scala/aqua/model/inline/ArrowInlinerSpec.scala
@@ -9,10 +9,8 @@ import cats.syntax.show.*
 import cats.data.{Chain, NonEmptyList, NonEmptyMap}
 import org.scalatest.flatspec.AnyFlatSpec
 import org.scalatest.matchers.should.Matchers
-import aqua.raw.value.ValueRaw
-import aqua.raw.value.CallArrowRaw
-import aqua.raw.arrow.FuncRaw
-import aqua.raw.arrow.ArrowRaw
+import aqua.raw.value.{CallArrowRaw, ValueRaw}
+import aqua.raw.arrow.{ArrowRaw, FuncRaw}
 
 class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
 
@@ -37,7 +35,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
 
     model.equalsOrShowDiff(
       CallServiceModel(
-        LiteralModel("\"dumb_srv_id\"", LiteralType.string),
+        LiteralModel.liftString("dumb_srv_id"),
         "dumb",
         CallModel(Nil, Nil)
       ).leaf
@@ -126,7 +124,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
                 CallModel.Export(canonModel.name, canonModel.`type`)
               ).leaf,
               CallServiceModel(
-                LiteralModel("\"test-service\"", LiteralType.string),
+                LiteralModel.liftString("test-service"),
                 "some-call",
                 CallModel(canonModel :: Nil, Nil)
               ).leaf
@@ -221,7 +219,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
     model.equalsOrShowDiff(
       RestrictionModel(streamVar.name, true).wrap(
         CallServiceModel(
-          LiteralModel("\"test-service\"", LiteralType.string),
+          LiteralModel.liftString("test-service"),
           "some-call",
           CallModel(streamModel :: Nil, Nil)
         ).leaf
@@ -306,7 +304,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
           .CallArrowModel(innerName)
           .wrap(
             CallServiceModel(
-              LiteralModel("\"test-service\"", LiteralType.string),
+              LiteralModel.liftString("test-service"),
               "get_records",
               CallModel(Nil, CallModel.Export(recordsModel.name, recordsModel.`type`) :: Nil)
             ).leaf
@@ -314,7 +312,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
         SeqModel.wrap(
           CanonicalizeModel(recordsModel, CallModel.Export(canonModel.name, canonType)).leaf,
           CallServiceModel(
-            LiteralModel("\"callbackSrv\"", LiteralType.string),
+            LiteralModel.liftString("callbackSrv"),
             "response",
             CallModel(canonModel :: Nil, Nil)
           ).leaf
@@ -469,7 +467,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
 
   /**
    * func inner() -> u16:
-   *        res = 42
+   *   res = 42
    *   <- res
    *
    * func outer() -> u16:
@@ -1051,7 +1049,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
     model.equalsOrShowDiff(
       SeqModel.wrap(
         CallServiceModel(
-          LiteralModel("\"getSrv\"", LiteralType.string),
+          LiteralModel.liftString("getSrv"),
           "getObj",
           CallModel(Nil, CallModel.Export(objectVar.name, objectVar.`type`) :: Nil)
         ).leaf,
@@ -1061,7 +1059,7 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
             SeqModel.wrap(
               FlattenModel(ValueModel.fromRaw(objectVarLambda), flattenObject.name).leaf,
               CallServiceModel(
-                LiteralModel("\"callbackSrv\"", LiteralType.string),
+                LiteralModel.liftString("callbackSrv"),
                 "response",
                 CallModel(ValueModel.fromRaw(flattenObject) :: Nil, Nil)
               ).leaf
@@ -1152,12 +1150,12 @@ class ArrowInlinerSpec extends AnyFlatSpec with Matchers {
     model.equalsOrShowDiff(
       SeqModel.wrap(
         CallServiceModel(
-          LiteralModel("\"getSrv\"", LiteralType.string),
+          LiteralModel.liftString("getSrv"),
           "getArr",
           CallModel(Nil, CallModel.Export(argArray.name, argArray.`type`) :: Nil)
         ).leaf,
         CallServiceModel(
-          LiteralModel("\"getSrv\"", LiteralType.string),
+          LiteralModel.liftString("getSrv"),
           "getIdx",
           CallModel(Nil, CallModel.Export(idxVar.name, idxVar.`type`) :: Nil)
         ).leaf
diff --git a/model/src/main/scala/aqua/model/OpModel.scala b/model/src/main/scala/aqua/model/OpModel.scala
index 75446336e..ab55a693b 100644
--- a/model/src/main/scala/aqua/model/OpModel.scala
+++ b/model/src/main/scala/aqua/model/OpModel.scala
@@ -39,7 +39,16 @@ object OpModel extends TreeNodeCompanion[OpModel] {
   }
 }
 
+/**
+ * Meta information embedded in a tree
+ */
 enum MetaModel extends OpModel {
+
+  /**
+   * Wraps subtree that was produced after inlining arrow
+   *
+   * @param name Name of arrow inlined
+   */
   case CallArrowModel(name: String)
 
   override def wrap(children: Tree*): Tree =
diff --git a/model/transform/src/main/scala/aqua/model/transform/funcop/OpTransform.scala b/model/transform/src/main/scala/aqua/model/transform/funcop/OpTransform.scala
index 046db0932..0e108db50 100644
--- a/model/transform/src/main/scala/aqua/model/transform/funcop/OpTransform.scala
+++ b/model/transform/src/main/scala/aqua/model/transform/funcop/OpTransform.scala
@@ -6,7 +6,15 @@ import cats.data.Chain
 import cats.free.Cofree
 import cats.Eval
 
+/**
+ * Base type for [[OpModel.Tree]] -> [[OpModel.Tree]] transformation
+ */
 trait OpTransform {
+
+  /**
+   * Transformation step
+   * (node, child results) => node result
+   */
   def folder: OpTransform.OpFolder
 
   def apply(tree: OpModel.Tree): Eval[OpModel.Tree] =