fix(slack): clarify formatting hints

CHANGELOG.md

@@ -33,6 +33,7 @@ Docs: https://docs.openclaw.ai
 - Slack: pass configured agent identity through draft preview sends so partial streaming replies keep custom username/avatar on the initial Slack message. Fixes #38235. (#38237) Thanks @lacymorrow.
 - Slack: support `allowBots: "mentions"` for bot-authored messages that mention the receiving bot, matching the documented Discord-style mode without accepting every bot message. Fixes #43587. (#43588) Thanks @raw34.
 - Slack: refresh private file URLs with `files.info` when inbound DM file events omit or stale attachment URLs, preventing file attachments from being dropped before media hydration. Fixes #50129. (#50200) Thanks @smartchainark.
+- Slack: add scoped message-tool formatting hints so agents use Markdown for plain sends and direct mrkdwn for Block Kit fields. Fixes #34609. (#50979) Thanks @carrotRakko.
 - Gateway/agents: keep structured reasons when active-run queueing fails and deprecate the legacy boolean queue helper, so steering and subagent wake diagnostics distinguish completed, non-streaming, and compacting runs. Fixes #80156. Thanks @markus-lassfolk.
 - Agents/UI: compact exec and tool progress rows by hiding redundant shell tool names, replacing known workspace paths with short context markers, and preserving Discord trace scrubbing for compact command lines.
 - ACPX: run and await the embedded ACP backend startup probe by default so the gateway `ready` signal no longer fires before the acpx runtime has either become usable or reported a probe failure; set `OPENCLAW_ACPX_RUNTIME_STARTUP_PROBE=0` to restore lazy startup. Fixes #79596. Thanks @bzelones.

extensions/slack/src/channel.test.ts

@@ -809,9 +809,15 @@ describe("slackPlugin agentPrompt", () => {
       },
     });
 
-    expect(hints).toEqual([
+    expect(hints).toContain(
       "- Slack interactive replies are disabled. If needed, ask to set `channels.slack.capabilities.interactiveReplies=true` (or the same under `channels.slack.accounts.<account>.capabilities`).",
-    ]);
+    );
+    expect(hints).toContain(
+      "- Slack plain text sends: write standard Markdown; OpenClaw converts it to Slack mrkdwn, including `**bold**`, headings, lists, and `[label](url)` links.",
+    );
+    expect(hints).toContain(
+      "- Slack Block Kit or presentation text fields are sent as Slack mrkdwn directly; use `*bold*`, `_italic_`, `~strike~`, `<url|label>` links, and avoid Markdown headings or pipe tables there.",
+    );
   });
 
   it("shows Slack interactive reply directives when enabled", () => {
@@ -836,6 +842,12 @@ describe("slackPlugin agentPrompt", () => {
     expect(hints).toContain(
       "- Slack selects: use `[[slack_select: Placeholder | Label:value, Other:other]]` to add a static select menu that routes the chosen value back as a Slack interaction system event.",
     );
+    expect(hints).toContain(
+      "- Slack plain text sends: write standard Markdown; OpenClaw converts it to Slack mrkdwn, including `**bold**`, headings, lists, and `[label](url)` links.",
+    );
+    expect(hints).toContain(
+      "- Slack Block Kit or presentation text fields are sent as Slack mrkdwn directly; use `*bold*`, `_italic_`, `~strike~`, `<url|label>` links, and avoid Markdown headings or pipe tables there.",
+    );
   });
 });
 

extensions/slack/src/shared.ts

@@ -104,7 +104,7 @@ export function createSlackPluginBase(params: {
         ],
       }),
       messageToolHints: ({ cfg, accountId }) =>
-        isSlackInteractiveRepliesEnabled({ cfg, accountId })
+        (isSlackInteractiveRepliesEnabled({ cfg, accountId })
           ? [
               "- Prefer Slack buttons/selects for 2-5 discrete choices or parameter picks instead of asking the user to type one.",
               "- Slack interactive replies: use `[[slack_buttons: Label:value, Other:other]]` to add action buttons that route clicks back as Slack interaction system events.",
@@ -112,7 +112,11 @@ export function createSlackPluginBase(params: {
             ]
           : [
               "- Slack interactive replies are disabled. If needed, ask to set `channels.slack.capabilities.interactiveReplies=true` (or the same under `channels.slack.accounts.<account>.capabilities`).",
-            ],
+            ]
+        ).concat([
+          "- Slack plain text sends: write standard Markdown; OpenClaw converts it to Slack mrkdwn, including `**bold**`, headings, lists, and `[label](url)` links.",
+          "- Slack Block Kit or presentation text fields are sent as Slack mrkdwn directly; use `*bold*`, `_italic_`, `~strike~`, `<url|label>` links, and avoid Markdown headings or pipe tables there.",
+        ]),
     },
     streaming: {
       blockStreamingCoalesceDefaults: { minChars: 1500, idleMs: 1000 },