diff --git a/src/script/descriptor.h b/src/script/descriptor.h
--- a/src/script/descriptor.h
+++ b/src/script/descriptor.h
@@ -57,10 +57,10 @@
      *      false, this is ignored.
      * provider: the provider to query for private keys in case of hardened
      *           derivation.
-     * output_script: the expanded scriptPubKeys will be put here.
+     * output_scripts: the expanded scriptPubKeys will be put here.
      * out: scripts and public keys necessary for solving the expanded
      * scriptPubKeys will be put here (may be equal to provider). cache: vector
-     * which will be overwritten with cache data necessary to-evaluate the
+     * which will be overwritten with cache data necessary to evaluate the
      * descriptor at this point without access to private keys.
      */
     virtual bool Expand(int pos, const SigningProvider &provider,
@@ -73,8 +73,8 @@
      *
      * pos: the position at which to expand the descriptor. If IsRange() is
      * false, this is ignored. cache: vector from which cached expansion data
-     * will be read. output_script: the expanded scriptPubKeys will be put here.
-     * out: scripts and public keys necessary for solving the expanded
+     * will be read. output_scripts: the expanded scriptPubKeys will be put
+     * here. out: scripts and public keys necessary for solving the expanded
      * scriptPubKeys will be put here (may be equal to provider).
      */
     virtual bool ExpandFromCache(int pos, const std::vector<uint8_t> &cache,
diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -394,10 +394,12 @@
 /** Base class for all Descriptor implementations. */
 class DescriptorImpl : public Descriptor {
     //! Public key arguments for this descriptor (size 1 for PK, PKH; any size
-    //! of Multisig).
+    //! for Multisig).
     const std::vector<std::unique_ptr<PubkeyProvider>> m_pubkey_args;
     //! The sub-descriptor argument (nullptr for everything but SH).
-    const std::unique_ptr<DescriptorImpl> m_script_arg;
+    //! In doc/descriptors.m this is referred to as SCRIPT expressions
+    //! sh(SCRIPT), and distinct from KEY expressions and ADDR expressions.
+    const std::unique_ptr<DescriptorImpl> m_subdescriptor_arg;
     //! The string name of the descriptor function.
     const std::string m_name;
 
@@ -410,11 +412,12 @@
      * A helper function to construct the scripts for this descriptor.
      *
      *  This function is invoked once for every CScript produced by evaluating
-     *  m_script_arg, or just once in case m_script_arg is nullptr.
+     *  m_subdescriptor_arg, or just once in case m_subdescriptor_arg is
+     nullptr.
 
      *  @param pubkeys The evaluations of the m_pubkey_args field.
-     *  @param script The evaluation of m_script_arg (or nullptr when
-     m_script_arg is nullptr).
+     *  @param script The evaluation of m_subdescriptor_arg (or nullptr when
+     m_subdescriptor_arg is nullptr).
      *  @param out A FlatSigningProvider to put scripts or public keys in that
      are necessary to the solver.
      *             The script arguments to this function are automatically
@@ -429,12 +432,12 @@
     DescriptorImpl(std::vector<std::unique_ptr<PubkeyProvider>> pubkeys,
                    std::unique_ptr<DescriptorImpl> script,
                    const std::string &name)
-        : m_pubkey_args(std::move(pubkeys)), m_script_arg(std::move(script)),
-          m_name(name) {}
+        : m_pubkey_args(std::move(pubkeys)),
+          m_subdescriptor_arg(std::move(script)), m_name(name) {}
 
     bool IsSolvable() const override {
-        if (m_script_arg) {
-            if (!m_script_arg->IsSolvable()) {
+        if (m_subdescriptor_arg) {
+            if (!m_subdescriptor_arg->IsSolvable()) {
                 return false;
             }
         }
@@ -447,8 +450,8 @@
                 return true;
             }
         }
-        if (m_script_arg) {
-            if (m_script_arg->IsRange()) {
+        if (m_subdescriptor_arg) {
+            if (m_subdescriptor_arg->IsRange()) {
                 return true;
             }
         }
@@ -474,12 +477,12 @@
             }
             ret += std::move(tmp);
         }
-        if (m_script_arg) {
+        if (m_subdescriptor_arg) {
             if (pos++) {
                 ret += ",";
             }
             std::string tmp;
-            if (!m_script_arg->ToStringHelper(arg, tmp, priv)) {
+            if (!m_subdescriptor_arg->ToStringHelper(arg, tmp, priv)) {
                 return false;
             }
             ret += std::move(tmp);
@@ -513,6 +516,8 @@
         // producing output in case of failure.
         for (const auto &p : m_pubkey_args) {
             entries.emplace_back();
+            // If we have a cache, we don't need GetPubKey to compute the public
+            // key. Pass in nullptr to signify only origin info is desired.
             if (!p->GetPubKey(pos, arg,
                               cache_read ? nullptr : &entries.back().first,
                               entries.back().second)) {
@@ -543,10 +548,11 @@
             }
         }
         std::vector<CScript> subscripts;
-        if (m_script_arg) {
+        if (m_subdescriptor_arg) {
             FlatSigningProvider subprovider;
-            if (!m_script_arg->ExpandHelper(pos, arg, cache_read, subscripts,
-                                            subprovider, cache_write)) {
+            if (!m_subdescriptor_arg->ExpandHelper(pos, arg, cache_read,
+                                                   subscripts, subprovider,
+                                                   cache_write)) {
                 return false;
             }
             out = Merge(out, subprovider);
@@ -561,7 +567,7 @@
                 std::make_pair<CPubKey, KeyOriginInfo>(
                     CPubKey(entry.first), std::move(entry.second)));
         }
-        if (m_script_arg) {
+        if (m_subdescriptor_arg) {
             for (const auto &subscript : subscripts) {
                 out.scripts.emplace(CScriptID(subscript), subscript);
                 std::vector<CScript> addscripts =