diff --git a/src/Runner.Worker/action_yaml.json b/src/Runner.Worker/action_yaml.json
index 82b24a695..7a2cf1781 100644
--- a/src/Runner.Worker/action_yaml.json
+++ b/src/Runner.Worker/action_yaml.json
@@ -108,19 +108,26 @@
             }
         },
         "composite-steps": {
-            "context": [
-                "github",
-                "strategy",
-                "matrix",
-                "steps",
-                "inputs",
-                "job",
-                "runner",
-                "env",
-                "hashFiles(1,255)"
-            ],
             "sequence": {
-                "item-type": "any"
+                "item-type": "composite-step"
+            }
+        },
+        "composite-step": {
+            "mapping": {
+                "properties": {
+                    "name": "string-steps-context",
+                    "id": "non-empty-string",
+                    "run": {
+                        "type": "string-steps-context",
+                        "required": true
+                    },
+                    "env": "step-env",
+                    "working-directory": "string-steps-context",
+                    "shell": {
+                        "type": "non-empty-string",
+                        "required": true
+                    }
+                }
             }
         },
         "container-runs-context": {
@@ -157,6 +164,37 @@
             "string": {
                 "require-non-empty": true
             }
+        },
+        "string-steps-context": {
+            "context": [
+                "github",
+                "inputs",
+                "strategy",
+                "matrix",
+                "steps",
+                "job",
+                "runner",
+                "env",
+                "hashFiles(1,255)"
+            ],
+            "string": {}
+        },
+        "step-env": {
+            "context": [
+                "github",
+                "inputs",
+                "strategy",
+                "matrix",
+                "steps",
+                "job",
+                "runner",
+                "env",
+                "hashFiles(1,255)"
+            ],
+            "mapping": {
+                "loose-key-type": "non-empty-string",
+                "loose-value-type": "string"
+            }
         }
     }
 }
\ No newline at end of file