feat: allow varying help texts for different subcommands

freqtrade/commands/arguments.py

@@ -3,6 +3,7 @@ This module contains the argument manager class
 """
 
 from argparse import ArgumentParser, Namespace, _ArgumentGroup
+from copy import deepcopy
 from functools import partial
 from pathlib import Path
 from typing import Any
@@ -349,7 +350,11 @@ class Arguments:
     def _build_args(self, optionlist: list[str], parser: ArgumentParser | _ArgumentGroup) -> None:
         for val in optionlist:
             opt = AVAILABLE_CLI_OPTIONS[val]
-            parser.add_argument(*opt.cli, dest=val, **opt.kwargs)
+            options = deepcopy(opt.kwargs)
+            help_text = options.pop("help", None)
+            if opt.fthelp and isinstance(opt.fthelp, dict):
+                help_text = opt.fthelp.get(parser.prog, help_text)
+            parser.add_argument(*opt.cli, dest=val, help=help_text, **options)
 
     def _build_subcommands(self) -> None:
         """

freqtrade/commands/cli_options.py

@@ -38,8 +38,14 @@ def check_int_nonzero(value: str) -> int:
 
 class Arg:
     # Optional CLI arguments
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, fthelp: dict[str, str] | None = None, **kwargs):
+        """
+        CLI Arguments - used to build subcommand parsers consistently.
+        :param fthelp: dict - fthelp per command - should be "freqtrade <command>": help_text
+            If not provided or not found, 'help' from kwargs is used instead.
+        """
         self.cli = args
+        self.fthelp = fthelp
         self.kwargs = kwargs
 
 
@@ -422,6 +428,14 @@ AVAILABLE_CLI_OPTIONS = {
     ),
     "candle_types": Arg(
         "--candle-types",
+        fthelp={
+            "freqtrade download-data": (
+                "Select candle type to download. "
+                "Defaults to the necessary candles for the selected trading mode "
+                "(e.g. 'spot' or ('futures', 'funding_rate' and 'mark') for futures)."
+            ),
+            "_": "Select candle type to convert. Defaults to all available types.",
+        },
         help="Select candle type to convert. Defaults to all available types.",
         choices=[c.value for c in CandleType],
         nargs="+",