At a minimum, help text should note this. This is true for things like addwitnessaddress especially.
{
    CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() != 1)
        throw std::runtime_error(
            "removeprunedfunds \"txid\"\n"
            "\nDeletes the specified transaction from the wallet. Meant for use with pruned wallets and as a companion to importprunedfunds. This will affect wallet balances.\n"
            "\nArguments:\n"
            "1. \"txid\"           (string, required) The hex-encoded id of the transaction you are deleting\n"
            "\nExamples:\n"
            + HelpExampleCli("removeprunedfunds", "\"a8d0c0184dde994a09ec054286f1ce581bebf46446a512166eae7628734ea0a5\"") +
            "\nAs a JSON-RPC call\n"
            + HelpExampleRpc("removeprunedfunds", "\"a8d0c0184dde994a09ec054286f1ce581bebf46446a512166eae7628734ea0a5\"")
        );
    LOCK2(cs_main, pwallet->cs_wallet);
    uint256 hash;
    hash.SetHex(request.params[0].get_str());