diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
index 99cd8f6d20..9447e9ff1a 100644
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -1,475 +1,485 @@
 // Copyright (c) 2017 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <key_io.h>
 #include <keystore.h>
 #include <pubkey.h>
 #include <rpc/protocol.h>
 #include <rpc/util.h>
 #include <tinyformat.h>
 #include <util/strencodings.h>
 
 #include <univalue.h>
 
 #include <boost/variant/static_visitor.hpp>
 
 InitInterfaces *g_rpc_interfaces = nullptr;
 
 // Converts a hex string to a public key if possible
 CPubKey HexToPubKey(const std::string &hex_in) {
     if (!IsHex(hex_in)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                            "Invalid public key: " + hex_in);
     }
     CPubKey vchPubKey(ParseHex(hex_in));
     if (!vchPubKey.IsFullyValid()) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                            "Invalid public key: " + hex_in);
     }
     return vchPubKey;
 }
 
 // Retrieves a public key for an address from the given CKeyStore
 CPubKey AddrToPubKey(const CChainParams &chainparams, CKeyStore *const keystore,
                      const std::string &addr_in) {
     CTxDestination dest = DecodeDestination(addr_in, chainparams);
     if (!IsValidDestination(dest)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                            "Invalid address: " + addr_in);
     }
     CKeyID key = GetKeyForDestination(*keystore, dest);
     if (key.IsNull()) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                            strprintf("%s does not refer to a key", addr_in));
     }
     CPubKey vchPubKey;
     if (!keystore->GetPubKey(key, vchPubKey)) {
         throw JSONRPCError(
             RPC_INVALID_ADDRESS_OR_KEY,
             strprintf("no full public key for address %s", addr_in));
     }
     if (!vchPubKey.IsFullyValid()) {
         throw JSONRPCError(RPC_INTERNAL_ERROR,
                            "Wallet contains an invalid public key");
     }
     return vchPubKey;
 }
 
 // Creates a multisig redeemscript from a given list of public keys and number
 // required.
 CScript CreateMultisigRedeemscript(const int required,
                                    const std::vector<CPubKey> &pubkeys) {
     // Gather public keys
     if (required < 1) {
         throw JSONRPCError(
             RPC_INVALID_PARAMETER,
             "a multisignature address must require at least one key to redeem");
     }
     if ((int)pubkeys.size() < required) {
         throw JSONRPCError(RPC_INVALID_PARAMETER,
                            strprintf("not enough keys supplied (got %u keys, "
                                      "but need at least %d to redeem)",
                                      pubkeys.size(), required));
     }
     if (pubkeys.size() > 16) {
         throw JSONRPCError(RPC_INVALID_PARAMETER,
                            "Number of keys involved in the multisignature "
                            "address creation > 16\nReduce the number");
     }
 
     CScript result = GetScriptForMultisig(required, pubkeys);
 
     if (result.size() > MAX_SCRIPT_ELEMENT_SIZE) {
         throw JSONRPCError(
             RPC_INVALID_PARAMETER,
             (strprintf("redeemScript exceeds size limit: %d > %d",
                        result.size(), MAX_SCRIPT_ELEMENT_SIZE)));
     }
 
     return result;
 }
 
 class DescribeAddressVisitor : public boost::static_visitor<UniValue> {
 public:
     explicit DescribeAddressVisitor() {}
 
     UniValue operator()(const CNoDestination &dest) const {
         return UniValue(UniValue::VOBJ);
     }
 
     UniValue operator()(const CKeyID &keyID) const {
         UniValue obj(UniValue::VOBJ);
         obj.pushKV("isscript", false);
         return obj;
     }
 
     UniValue operator()(const CScriptID &scriptID) const {
         UniValue obj(UniValue::VOBJ);
         obj.pushKV("isscript", true);
         return obj;
     }
 };
 
 UniValue DescribeAddress(const CTxDestination &dest) {
     return boost::apply_visitor(DescribeAddressVisitor(), dest);
 }
 
 RPCErrorCode RPCErrorFromTransactionError(TransactionError terr) {
     switch (terr) {
         case TransactionError::MEMPOOL_REJECTED:
             return RPC_TRANSACTION_REJECTED;
         case TransactionError::ALREADY_IN_CHAIN:
             return RPC_TRANSACTION_ALREADY_IN_CHAIN;
         case TransactionError::P2P_DISABLED:
             return RPC_CLIENT_P2P_DISABLED;
         case TransactionError::INVALID_PSBT:
         case TransactionError::PSBT_MISMATCH:
             return RPC_INVALID_PARAMETER;
         case TransactionError::SIGHASH_MISMATCH:
             return RPC_DESERIALIZATION_ERROR;
         default:
             break;
     }
     return RPC_TRANSACTION_ERROR;
 }
 
 UniValue JSONRPCTransactionError(TransactionError terr,
                                  const std::string &err_string) {
     if (err_string.length() > 0) {
         return JSONRPCError(RPCErrorFromTransactionError(terr), err_string);
     } else {
         return JSONRPCError(RPCErrorFromTransactionError(terr),
                             TransactionErrorString(terr));
     }
 }
 
 struct Section {
     Section(const std::string &left, const std::string &right)
         : m_left{left}, m_right{right} {}
     const std::string m_left;
     const std::string m_right;
 };
 
 struct Sections {
     std::vector<Section> m_sections;
     size_t m_max_pad{0};
 
     void PushSection(const Section &s) {
         m_max_pad = std::max(m_max_pad, s.m_left.size());
         m_sections.push_back(s);
     }
 
     enum class OuterType {
         ARR,
         OBJ,
         // Only set on first recursion
         NAMED_ARG,
     };
 
     void Push(const RPCArg &arg, const size_t current_indent = 5,
               const OuterType outer_type = OuterType::NAMED_ARG) {
         const auto indent = std::string(current_indent, ' ');
         const auto indent_next = std::string(current_indent + 2, ' ');
         switch (arg.m_type) {
             case RPCArg::Type::STR_HEX:
             case RPCArg::Type::STR:
             case RPCArg::Type::NUM:
             case RPCArg::Type::AMOUNT:
             case RPCArg::Type::BOOL: {
                 // Nothing more to do for non-recursive types on first recursion
                 if (outer_type == OuterType::NAMED_ARG) {
                     return;
                 }
                 auto left = indent;
                 if (arg.m_type_str.size() != 0 &&
                     outer_type == OuterType::OBJ) {
                     left += "\"" + arg.m_name + "\": " + arg.m_type_str.at(0);
                 } else {
                     left += outer_type == OuterType::OBJ
                                 ? arg.ToStringObj(/* oneline */ false)
                                 : arg.ToString(/* oneline */ false);
                 }
                 left += ",";
                 PushSection({left, arg.ToDescriptionString(
                                        /* implicitly_required */ outer_type ==
                                        OuterType::ARR)});
                 break;
             }
             case RPCArg::Type::OBJ:
             case RPCArg::Type::OBJ_USER_KEYS: {
                 const auto right =
                     outer_type == OuterType::NAMED_ARG
                         ? ""
                         : arg.ToDescriptionString(
                               /* implicitly_required */ outer_type ==
                               OuterType::ARR);
                 PushSection({indent + "{", right});
                 for (const auto &arg_inner : arg.m_inner) {
                     Push(arg_inner, current_indent + 2, OuterType::OBJ);
                 }
                 if (arg.m_type != RPCArg::Type::OBJ) {
                     PushSection({indent_next + "...", ""});
                 }
                 PushSection(
                     {indent + "}" +
                          (outer_type != OuterType::NAMED_ARG ? "," : ""),
                      ""});
                 break;
             }
             case RPCArg::Type::ARR: {
                 auto left = indent;
                 left += outer_type == OuterType::OBJ
                             ? "\"" + arg.m_name + "\": "
                             : "";
                 left += "[";
                 const auto right =
                     outer_type == OuterType::NAMED_ARG
                         ? ""
                         : arg.ToDescriptionString(
                               /* implicitly_required */ outer_type ==
                               OuterType::ARR);
                 PushSection({left, right});
                 for (const auto &arg_inner : arg.m_inner) {
                     Push(arg_inner, current_indent + 2, OuterType::ARR);
                 }
                 PushSection({indent_next + "...", ""});
                 PushSection(
                     {indent + "]" +
                          (outer_type != OuterType::NAMED_ARG ? "," : ""),
                      ""});
                 break;
             }
 
                 // no default case, so the compiler can warn about missing cases
         }
     }
 
     std::string ToString() const {
         std::string ret;
         const size_t pad = m_max_pad + 4;
         for (const auto &s : m_sections) {
             if (s.m_right.empty()) {
                 ret += s.m_left;
                 ret += "\n";
                 continue;
             }
 
             std::string left = s.m_left;
             left.resize(pad, ' ');
             ret += left;
 
             // Properly pad after newlines
             std::string right;
             size_t begin = 0;
             size_t new_line_pos = s.m_right.find_first_of('\n');
             while (true) {
                 right += s.m_right.substr(begin, new_line_pos - begin);
                 if (new_line_pos == std::string::npos) {
                     // No new line
                     break;
                 }
                 right += "\n" + std::string(pad, ' ');
                 begin = s.m_right.find_first_not_of(' ', new_line_pos + 1);
                 if (begin == std::string::npos) {
                     break; // Empty line
                 }
                 new_line_pos = s.m_right.find_first_of('\n', begin + 1);
             }
             ret += right;
             ret += "\n";
         }
         return ret;
     }
 };
 
+RPCHelpMan::RPCHelpMan(const std::string &name, const std::string &description,
+                       const std::vector<RPCArg> &args)
+    : m_name{name}, m_description{description}, m_args{args} {
+    std::set<std::string> named_args;
+    for (const auto &arg : m_args) {
+        // Should have unique named arguments
+        CHECK_NONFATAL(named_args.insert(arg.m_name).second);
+    }
+}
+
 std::string RPCHelpMan::ToString() const {
     std::string ret;
 
     // Oneline summary
     ret += m_name;
     bool was_optional{false};
     for (const auto &arg : m_args) {
         ret += " ";
         if (arg.m_optional) {
             if (!was_optional) {
                 ret += "( ";
             }
             was_optional = true;
         } else {
             if (was_optional) {
                 ret += ") ";
             }
             was_optional = false;
         }
         ret += arg.ToString(/* oneline */ true);
     }
     if (was_optional) {
         ret += " )";
     }
     ret += "\n";
 
     // Description
     ret += m_description;
 
     // Arguments
     Sections sections;
     for (size_t i{0}; i < m_args.size(); ++i) {
         const auto &arg = m_args.at(i);
 
         if (i == 0) {
             ret += "\nArguments:\n";
         }
 
         // Push named argument name and description
         sections.m_sections.emplace_back(std::to_string(i + 1) + ". " +
                                              arg.m_name,
                                          arg.ToDescriptionString());
         sections.m_max_pad = std::max(sections.m_max_pad,
                                       sections.m_sections.back().m_left.size());
 
         // Recursively push nested args
         sections.Push(arg);
     }
     ret += sections.ToString();
 
     return ret;
 }
 
 std::string RPCArg::ToDescriptionString(const bool implicitly_required) const {
     std::string ret;
     ret += "(";
     if (m_type_str.size() != 0) {
         ret += m_type_str.at(1);
     } else {
         switch (m_type) {
             case Type::STR_HEX:
             case Type::STR: {
                 ret += "string";
                 break;
             }
             case Type::NUM: {
                 ret += "numeric";
                 break;
             }
             case Type::AMOUNT: {
                 ret += "numeric or string";
                 break;
             }
             case Type::BOOL: {
                 ret += "boolean";
                 break;
             }
             case Type::OBJ:
             case Type::OBJ_USER_KEYS: {
                 ret += "json object";
                 break;
             }
             case Type::ARR: {
                 ret += "json array";
                 break;
             }
 
                 // no default case, so the compiler can warn about missing cases
         }
     }
     if (!implicitly_required) {
         ret += ", ";
         if (m_optional) {
             ret += "optional";
             if (!m_default_value.empty()) {
                 ret += ", default=" + m_default_value;
             } else {
                 // TODO enable this assert, when all optional parameters have
                 // their default value documented
                 // assert(false);
             }
         } else {
             ret += "required";
             // Default value is ignored, and must not be present
             assert(m_default_value.empty());
         }
     }
     ret += ")";
     ret += m_description.empty() ? "" : " " + m_description;
     return ret;
 }
 
 std::string RPCArg::ToStringObj(const bool oneline) const {
     std::string res;
     res += "\"";
     res += m_name;
     if (oneline) {
         res += "\":";
     } else {
         res += "\": ";
     }
     switch (m_type) {
         case Type::STR:
             return res + "\"str\"";
         case Type::STR_HEX:
             return res + "\"hex\"";
         case Type::NUM:
             return res + "n";
         case Type::AMOUNT:
             return res + "amount";
         case Type::BOOL:
             return res + "bool";
         case Type::ARR:
             res += "[";
             for (const auto &i : m_inner) {
                 res += i.ToString(oneline) + ",";
             }
             return res + "...]";
         case Type::OBJ:
         case Type::OBJ_USER_KEYS:
             // Currently unused, so avoid writing dead code
             assert(false);
 
             // no default case, so the compiler can warn about missing cases
     }
     assert(false);
 }
 
 std::string RPCArg::ToString(const bool oneline) const {
     if (oneline && !m_oneline_description.empty()) {
         return m_oneline_description;
     }
 
     switch (m_type) {
         case Type::STR_HEX:
         case Type::STR: {
             return "\"" + m_name + "\"";
         }
         case Type::NUM:
         case Type::AMOUNT:
         case Type::BOOL: {
             return m_name;
         }
         case Type::OBJ:
         case Type::OBJ_USER_KEYS: {
             std::string res;
             for (size_t i = 0; i < m_inner.size();) {
                 res += m_inner[i].ToStringObj(oneline);
                 if (++i < m_inner.size()) {
                     res += ",";
                 }
             }
             if (m_type == Type::OBJ) {
                 return "{" + res + "}";
             } else {
                 return "{" + res + ",...}";
             }
         }
         case Type::ARR: {
             std::string res;
             for (const auto &i : m_inner) {
                 res += i.ToString(oneline) + ",";
             }
             return "[" + res + "...]";
         }
 
             // no default case, so the compiler can warn about missing cases
     }
     assert(false);
 }
diff --git a/src/rpc/util.h b/src/rpc/util.h
index cd7b7aa6c6..7155bd719a 100644
--- a/src/rpc/util.h
+++ b/src/rpc/util.h
@@ -1,130 +1,129 @@
 // Copyright (c) 2017 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_RPC_UTIL_H
 #define BITCOIN_RPC_UTIL_H
 
 #include <node/transaction.h>
 #include <script/standard.h> // For CTxDestination
 #include <util/check.h>
 
 #include <string>
 #include <vector>
 
 class CChainParams;
 class CKeyStore;
 class CPubKey;
 class CScript;
 struct InitInterfaces;
 class UniValue;
 
 //! Pointers to interfaces that need to be accessible from RPC methods. Due to
 //! limitations of the RPC framework, there's currently no direct way to pass in
 //! state to RPC method implementations.
 extern InitInterfaces *g_rpc_interfaces;
 
 CPubKey HexToPubKey(const std::string &hex_in);
 CPubKey AddrToPubKey(const CChainParams &chainparams, CKeyStore *const keystore,
                      const std::string &addr_in);
 CScript CreateMultisigRedeemscript(const int required,
                                    const std::vector<CPubKey> &pubkeys);
 
 UniValue DescribeAddress(const CTxDestination &dest);
 
 RPCErrorCode RPCErrorFromTransactionError(TransactionError terr);
 UniValue JSONRPCTransactionError(TransactionError terr,
                                  const std::string &err_string = "");
 
 struct RPCArg {
     enum class Type {
         OBJ,
         ARR,
         STR,
         NUM,
         BOOL,
         //! Special type where the user must set the keys e.g. to define
         //! multiple addresses; as opposed to e.g. an options object where the
         //! keys are predefined
         OBJ_USER_KEYS,
         //! Special type representing a floating point amount (can be either NUM
         //! or STR)
         AMOUNT,
         //! Special type that is a STR with only hex chars
         STR_HEX,
     };
     //! The name of the arg (can be empty for inner args)
     const std::string m_name;
     const Type m_type;
     //! Only used for arrays or dicts
     const std::vector<RPCArg> m_inner;
     const bool m_optional;
     const std::string m_default_value; //!< Only used for optional args
     const std::string m_description;
     //! Should be empty unless it is supposed to override the auto-generated
     //! summary line
     const std::string m_oneline_description;
 
     //! Should be empty unless it is supposed to override the
     //! auto-generated type strings. Vector length is either 0
     //! or 2, m_type_str.at(0) will override the type of the
     //! value in a key-value pair, m_type_str.at(1) will
     //! override the type in the argument description.
     const std::vector<std::string> m_type_str;
 
     RPCArg(const std::string &name, const Type &type, const bool opt,
            const std::string &default_val, const std::string &description,
            const std::string &oneline_description = "",
            const std::vector<std::string> &type_str = {})
         : m_name{name}, m_type{type}, m_optional{opt},
           m_default_value{default_val}, m_description{description},
           m_oneline_description{oneline_description}, m_type_str{type_str} {
         CHECK_NONFATAL(type != Type::ARR && type != Type::OBJ);
     }
 
     RPCArg(const std::string &name, const Type &type, const bool opt,
            const std::string &default_val, const std::string &description,
            const std::vector<RPCArg> &inner,
            const std::string &oneline_description = "",
            const std::vector<std::string> &type_str = {})
         : m_name{name}, m_type{type}, m_inner{inner}, m_optional{opt},
           m_default_value{default_val}, m_description{description},
           m_oneline_description{oneline_description}, m_type_str{type_str} {
         CHECK_NONFATAL(type == Type::ARR || type == Type::OBJ);
     }
 
     /**
      * Return the type string of the argument.
      * Set oneline to allow it to be overrided by a custom oneline type string
      * (m_oneline_description).
      */
     std::string ToString(bool oneline) const;
     /**
      * Return the type string of the argument when it is in an object (dict).
      * Set oneline to get the oneline representation (less whitespace)
      */
     std::string ToStringObj(bool oneline) const;
     /**
      * Return the description string, including the argument type and whether
      * the argument is required.
      * implicitly_required is set for arguments in an array, which are neither
      * optional nor required.
      */
     std::string ToDescriptionString(bool implicitly_required = false) const;
 };
 
 class RPCHelpMan {
 public:
     RPCHelpMan(const std::string &name, const std::string &description,
-               const std::vector<RPCArg> &args)
-        : m_name{name}, m_description{description}, m_args{args} {}
+               const std::vector<RPCArg> &args);
 
     std::string ToString() const;
 
 private:
     const std::string m_name;
     const std::string m_description;
     const std::vector<RPCArg> m_args;
 };
 
 #endif // BITCOIN_RPC_UTIL_H