diff --git a/.changeset/fluffy-jokes-repair.md b/.changeset/fluffy-jokes-repair.md
new file mode 100644
index 00000000000..c07db41ac3d
--- /dev/null
+++ b/.changeset/fluffy-jokes-repair.md
@@ -0,0 +1,5 @@
+---
+"@effect/platform": patch
+---
+
+Fix HttpApi discarding annotations from Union and Literal schemas
diff --git a/packages/platform/src/HttpApiSchema.ts b/packages/platform/src/HttpApiSchema.ts
index 5001e3d045f..64d3df752fb 100644
--- a/packages/platform/src/HttpApiSchema.ts
+++ b/packages/platform/src/HttpApiSchema.ts
@@ -221,18 +221,16 @@ export const getStatusError = <A extends Schema.Schema.All>(self: A): number =>
  * @internal
  */
 export const extractUnionTypes = (ast: AST.AST): ReadonlyArray<AST.AST> => {
-  function process(ast: AST.AST): void {
-    if (AST.isUnion(ast)) {
-      for (const type of ast.types) {
-        process(type)
-      }
+  if (AST.isUnion(ast)) {
+    const types = ast.types.flatMap((type) => extractUnionTypes(type))
+    if (Reflect.ownKeys(ast.annotations).length === 0) {
+      return types
     } else {
-      out.push(ast)
+      return [AST.Union.make(types, ast.annotations)]
     }
+  } else {
+    return [ast]
   }
-  const out: Array<AST.AST> = []
-  process(ast)
-  return out
 }
 
 /** @internal */
diff --git a/packages/platform/test/OpenApi.test.ts b/packages/platform/test/OpenApi.test.ts
index a067798a7b4..31001394de5 100644
--- a/packages/platform/test/OpenApi.test.ts
+++ b/packages/platform/test/OpenApi.test.ts
@@ -938,6 +938,40 @@ describe("OpenApi", () => {
             }
           })
         })
+
+        it("Schema.Literal annotations", () => {
+          const api = HttpApi.make("Api").add(
+            HttpApiGroup.make("group").add(
+              HttpApiEndpoint.get("endpoint")`/`
+                .addSuccess(Schema.Literal("a", "b").annotations({ title: "Letter" }))
+            )
+          )
+          expectSpecPaths(api, {
+            "/": {
+              "get": {
+                "tags": ["group"],
+                "operationId": "group.endpoint",
+                "parameters": [],
+                "security": [],
+                "responses": {
+                  "200": {
+                    "description": "Success",
+                    "content": {
+                      "application/json": {
+                        "schema": {
+                          "type": "string",
+                          "enum": ["a", "b"],
+                          "title": "Letter"
+                        }
+                      }
+                    }
+                  },
+                  "400": HttpApiDecodeError
+                }
+              }
+            }
+          })
+        })
       })
 
       describe("addSuccess + withEncoding", () => {