diff --git a/queries/inconsistent-action-input.ql b/queries/inconsistent-action-input.ql
new file mode 100644
index 000000000..ec24fed06
--- /dev/null
+++ b/queries/inconsistent-action-input.ql
@@ -0,0 +1,51 @@
+/**
+ * @name Inconsistent action input
+ * @description If multiple actions define an input with the same name, then the input
+ *   must be defined in an identical way to avoid confusion for the user.
+ *   This also makes writing queries like required-action-input.ql easier.
+ * @kind problem
+ * @problem.severity error
+ * @id javascript/codeql-action/inconsistent-action-input
+ */
+
+import javascript
+
+/**
+ * A declaration of a github action.
+ */
+class ActionDeclaration extends File {
+  ActionDeclaration() {
+    getRelativePath().matches("%/action.yml")
+  }
+
+  /**
+   * The name of the action.
+   */
+  string getName() {
+    result = getRelativePath().regexpCapture("(.*)/action.yml", 1)
+  }
+
+  YAMLDocument getRootNode() {
+    result.getFile() = this
+  }
+
+  YAMLValue getInput(string inputName) {
+    result = getRootNode().(YAMLMapping).lookup("inputs").(YAMLMapping).lookup(inputName)
+  }
+}
+
+predicate areNotEquivalent(YAMLValue x, YAMLValue y) {
+  x.getTag() != y.getTag()
+  or
+  x.(YAMLScalar).getValue() != y.(YAMLScalar).getValue()
+  or
+  x.getNumChild() != y.getNumChild()
+  or
+  exists(int i | areNotEquivalent(x.getChild(i), y.getChild(i)))
+}
+
+from ActionDeclaration actionA, ActionDeclaration actionB, string inputName
+where actionA.getName() < actionB.getName() // prevent duplicates which are permutations of the names
+  and areNotEquivalent(actionA.getInput(inputName), actionB.getInput(inputName))
+select actionA, "Action $@ and action $@ both declare input $@, however their definitions are not identical. This may be confusing to users.",
+  actionA, actionA.getName(), actionB, actionB.getName(), inputName, inputName
diff --git a/queries/required-action-input.ql b/queries/required-action-input.ql
new file mode 100644
index 000000000..8bf9c565e
--- /dev/null
+++ b/queries/required-action-input.ql
@@ -0,0 +1,93 @@
+/**
+ * @name Required action input
+ * @description For action inputs the core.input represents input with no value as the emptystring.
+ *   This doesn't promote good type checking. Instead, use either actions-util.getOptionalInput or
+ *   actions-util.getRequiredInput depending on if the input always has a value or not. The input
+ *   will always have a value if it is required or has a default value.
+ * @kind problem
+ * @problem.severity error
+ * @id javascript/codeql-action/required-action-input
+ */
+
+import javascript
+
+/**
+ * A declaration of a github action.
+ */
+class ActionDeclaration extends File {
+  ActionDeclaration() {
+    getRelativePath().matches("%/action.yml")
+  }
+
+  YAMLDocument getRootNode() {
+    result.getFile() = this
+  }
+
+  /**
+   * The name of any input to this action.
+   */
+  string getAnInput() {
+    result = getRootNode().(YAMLMapping).lookup("inputs").(YAMLMapping).getKey(_).(YAMLString).getValue()
+  }
+
+  /**
+   * The given input always has a value, either because it is required,
+   * or because it has a default value.
+   */
+  predicate inputAlwaysHasValue(string input) {
+    exists(YAMLMapping value |
+      value = getRootNode().(YAMLMapping).lookup("inputs").(YAMLMapping).lookup(input) and
+      (exists(value.lookup("default")) or
+       value.lookup("required").(YAMLBool).getBoolValue() = true))
+  }
+
+  /**
+   * The function that is the entrypoint to this action.
+   */
+  FunctionDeclStmt getEntrypoint() {
+    result.getFile().getRelativePath() = getRootNode().
+      (YAMLMapping).lookup("runs").
+      (YAMLMapping).lookup("main").
+      (YAMLString).getValue().regexpReplaceAll("\\.\\./lib/(.*)\\.js", "src/$1.ts") and
+    result.getName() = "run"
+  }
+}
+
+/**
+ * An import from "@actions/core"
+ */
+class ActionsLibImport extends ImportDeclaration {
+  ActionsLibImport() {
+    getImportedPath().getValue() = "@actions/core"
+  }
+
+  Variable getAProvidedVariable() {
+    result = getASpecifier().getLocal().getVariable()
+  }
+}
+
+/**
+ * A call to the core.getInput method.
+ */
+class CoreGetInputMethodCallExpr extends MethodCallExpr {
+  CoreGetInputMethodCallExpr() {
+    getMethodName() = "getInput" and
+    exists(ActionsLibImport libImport |
+      this.getReceiver() = libImport.getAProvidedVariable().getAnAccess() or
+      this.getReceiver().(PropAccess).getBase() = libImport.getAProvidedVariable().getAnAccess())
+  }
+
+  /**
+   * The name of the input being accessed.
+   */
+  string getInputName() {
+    result = getArgument(0).(StringLiteral).getValue()
+  }
+}
+
+from ActionDeclaration action, CoreGetInputMethodCallExpr getInputCall, string inputName, string alternateFunction
+where action.getAnInput() = inputName
+  and getInputCall.getInputName() = inputName
+  and ((action.inputAlwaysHasValue(inputName) and alternateFunction = "getRequiredInput")
+    or (not action.inputAlwaysHasValue(inputName) and alternateFunction = "geOptionalInput"))
+select getInputCall, "This input may be undefined. Please use actions-util.$@ instead.", alternateFunction, alternateFunction
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