diff --git a/packages/simplex-chat-python/examples/squaring_bot.py b/packages/simplex-chat-python/examples/squaring_bot.py
index 296b51347e..4d062ad718 100644
--- a/packages/simplex-chat-python/examples/squaring_bot.py
+++ b/packages/simplex-chat-python/examples/squaring_bot.py
@@ -26,7 +26,15 @@ bot = Bot(
     profile=BotProfile(display_name="Squaring bot"),
     db=SqliteDb(file_prefix="./squaring_bot"),
     welcome="Send me a number, I'll square it.",
-    commands=[BotCommand(keyword="help", label="Show help")],
+    commands=[
+        # `params=None` (default): the client SENDS `/help` immediately
+        # when the user taps it in the commands menu.
+        BotCommand(keyword="help", label="Show help"),
+        # `params="<number>"`: the client PASTES `/square <number>`
+        # into the input box and positions the cursor at the end. The
+        # user replaces `<number>` with the actual number and sends.
+        BotCommand(keyword="square", label="Square a number", params="<number>"),
+    ],
 )
 
 NUMBER_RE = re.compile(r"^-?\d+(\.\d+)?$")
@@ -48,5 +56,19 @@ async def help_cmd(msg: Message, _cmd: ParsedCommand) -> None:
     await msg.reply("Send a number, I'll square it.")
 
 
+@bot.on_command("square")
+async def square_cmd(msg: Message, cmd: ParsedCommand) -> None:
+    """Demonstrates the `params` flow: `cmd.args` is the trimmed text
+    AFTER `/square`. When the user tapped the menu entry above, the
+    client pasted `/square <number>` and the user replaced
+    `<number>` with the actual value before sending."""
+    try:
+        n = float(cmd.args)
+    except ValueError:
+        await msg.reply(f"Usage: /square <number> (got {cmd.args!r})")
+        return
+    await msg.reply(f"{n} * {n} = {n * n}")
+
+
 if __name__ == "__main__":
     bot.run()
diff --git a/packages/simplex-chat-python/src/simplex_chat/bot.py b/packages/simplex-chat-python/src/simplex_chat/bot.py
index fb511e2818..4e385493b2 100644
--- a/packages/simplex-chat-python/src/simplex_chat/bot.py
+++ b/packages/simplex-chat-python/src/simplex_chat/bot.py
@@ -33,8 +33,38 @@ from .types import T
 
 @dataclass(slots=True)
 class BotCommand:
+    """One entry in the bot's advertised slash-command list (wire-side
+    `groupPreferences.commands` or profile `preferences.commands`).
+
+    `keyword` and `label` are required: `keyword` is what the user
+    types after `/`; `label` is the human-readable description shown
+    next to the keyword in the SimpleX client's commands menu.
+
+    `params` is an optional placeholder string that controls how the
+    client behaves when the user taps the command in the menu:
+
+      * `params=None` (default) — the client SENDS `/<keyword>`
+        immediately on tap; no input-box detour. Use this for
+        zero-argument commands (`/help`, `/ping`) where the action is
+        unambiguous.
+
+      * `params="<value>"` — the client PASTES `/<keyword> <params>`
+        into the input box and positions the cursor at the end. The
+        user edits the placeholder and sends. Use this for commands
+        that take a required argument (`/review <pr-url>`,
+        `/order <number>`) so the user sees the expected shape
+        without having to remember it.
+
+    Mirrors `CBCCommand` in the Haskell core
+    (`Simplex.Chat.Types.Preferences`) and the wire TypedDict
+    `ChatBotCommand_command`. Both SimpleX clients (Android/Kotlin
+    and iOS/Swift) implement the paste-vs-send branch on the
+    `params` field; see `CommandsMenuView.{kt,swift}` for the
+    reference UI behaviour.
+    """
     keyword: str
     label: str
+    params: str | None = None
 
 
 class Bot(Client):
@@ -145,10 +175,24 @@ class Bot(Client):
             "files": {"allow": "yes" if self._allow_files else "no"},
         }
         if self._commands:
-            prefs["commands"] = [
-                {"type": "command", "keyword": c.keyword, "label": c.label}
-                for c in self._commands
-            ]
+            cmds: list[T.ChatBotCommand] = []
+            for c in self._commands:
+                entry: T.ChatBotCommand_command = {
+                    "type": "command",
+                    "keyword": c.keyword,
+                    "label": c.label,
+                }
+                # `params` is `NotRequired[str]` on the wire; omit the
+                # key entirely when None so the Haskell parser sees
+                # `Nothing` rather than `Just ""`. The two have
+                # different client semantics: `Nothing` (`params=None`)
+                # triggers an immediate send on tap; `Just ""` would
+                # paste `/<keyword> ` (with a trailing space) into the
+                # input box, which is rarely what the operator wants.
+                if c.params is not None:
+                    entry["params"] = c.params
+                cmds.append(entry)
+            prefs["commands"] = cmds
         p["preferences"] = prefs
         p["peerType"] = "bot"
         return p
diff --git a/packages/simplex-chat-python/tests/test_bot_registration.py b/packages/simplex-chat-python/tests/test_bot_registration.py
index f6f245c344..06837bdc07 100644
--- a/packages/simplex-chat-python/tests/test_bot_registration.py
+++ b/packages/simplex-chat-python/tests/test_bot_registration.py
@@ -86,8 +86,63 @@ def test_bot_profile_to_wire_with_commands():
     )
     cmds = bot._profile_to_wire().get("preferences", {}).get("commands") or []
     assert len(cmds) == 2
+    # `params` defaults to None and must be ABSENT from the wire dict
+    # (not present as `null`/`""`) so the Haskell parser sees
+    # `Nothing` and the SimpleX client sends the bare `/keyword` on
+    # tap rather than pasting a trailing-space placeholder.
     assert cmds[0] == {"type": "command", "keyword": "ping", "label": "Ping bot"}
     assert cmds[1] == {"type": "command", "keyword": "help", "label": "Show help"}
+    assert "params" not in cmds[0]
+    assert "params" not in cmds[1]
+
+
+def test_bot_command_params_emits_on_wire():
+    """When `BotCommand.params` is set, the wire dict carries it as
+    `params: <str>`. The SimpleX client (verified against
+    `CommandsMenuView.kt:153-161` and `CommandsMenuView.swift:117-128`
+    in simplex-chat 6.5) then pastes `/<keyword> <params>` into the
+    input box on tap, positions the cursor at the end, and lets the
+    user edit before sending. Use this for commands that take a
+    required argument (`/review <pr-url>`)."""
+    bot = Bot(
+        profile=BotProfile(display_name="x"),
+        db=SqliteDb(file_prefix="/tmp/test"),
+        commands=[
+            BotCommand(keyword="review", label="Review PR", params="<pr-url>"),
+            BotCommand(keyword="order", label="Place order", params="<order number>"),
+        ],
+    )
+    cmds = bot._profile_to_wire().get("preferences", {}).get("commands") or []
+    assert cmds[0] == {
+        "type": "command",
+        "keyword": "review",
+        "label": "Review PR",
+        "params": "<pr-url>",
+    }
+    assert cmds[1] == {
+        "type": "command",
+        "keyword": "order",
+        "label": "Place order",
+        "params": "<order number>",
+    }
+
+
+def test_bot_command_distinguishes_none_from_empty_params():
+    """`params=None` (immediate send) and `params=""` (paste with
+    trailing space) are semantically different on the client side.
+    Verify the wire form preserves the distinction: None → key
+    absent; empty string → key present with empty value."""
+    bot = Bot(
+        profile=BotProfile(display_name="x"),
+        db=SqliteDb(file_prefix="/tmp/test"),
+        commands=[
+            BotCommand(keyword="send", label="Send", params=None),
+            BotCommand(keyword="paste", label="Paste", params=""),
+        ],
+    )
+    cmds = bot._profile_to_wire().get("preferences", {}).get("commands") or []
+    assert "params" not in cmds[0]
+    assert cmds[1].get("params") == ""
 
 
 def test_client_profile_to_wire_has_no_bot_extras():