diff --git a/CHANGELOG.md b/CHANGELOG.md
index e7b6a078a9b..d8f15ff26a7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,7 @@ Docs: https://docs.openclaw.ai
 ### Fixes
 
 - Models/UI: hide unauthenticated providers from the default Web chat, `/models`, and model setup pickers while keeping explicit full-catalog browse paths through `view: "all"`, `/models <provider> all`, and `models list --all`. Fixes #74423. Thanks @guarismo and @SymbolStar.
+- Slack/tools: expose `fileId` in the shared message tool schema so `download-file` can receive Slack attachment IDs from inbound placeholders. Fixes #45574. Thanks @chadvegas.
 - Exec: reject invalid per-call `host` values instead of silently falling back to the default target, so hostname-like values fail before commands run. Fixes #74426. Thanks @scr00ge-00 and @vyctorbrzezowski.
 - Google/Gemini: send non-empty placeholder content when a Gemini run is triggered with empty or filtered user content, avoiding `contents is not specified` API errors. Thanks @CaoYuhaoCarl.
 - Heartbeat: preserve non-task `HEARTBEAT.md` context around `tasks:` blocks and apply `agents.defaults.heartbeat` to all agents unless per-agent heartbeat entries restrict scope. Thanks @Sekhar03.
diff --git a/src/agents/tools/message-tool.test.ts b/src/agents/tools/message-tool.test.ts
index 31eee4a1386..80bae379c46 100644
--- a/src/agents/tools/message-tool.test.ts
+++ b/src/agents/tools/message-tool.test.ts
@@ -699,6 +699,29 @@ describe("message tool schema scoping", () => {
       expect.arrayContaining(["send", "broadcast"]),
     );
   });
+
+  it("advertises Slack download-file fileId in scoped schemas", () => {
+    const slackFilePlugin = createChannelPlugin({
+      id: "slack",
+      label: "Slack",
+      docsPath: "/channels/slack",
+      blurb: "Slack test plugin.",
+      actions: ["download-file"],
+    });
+
+    setActivePluginRegistry(
+      createTestRegistry([{ pluginId: "slack", source: "test", plugin: slackFilePlugin }]),
+    );
+
+    const tool = createMessageTool({
+      config: {} as never,
+      currentChannelProvider: "slack",
+    });
+    const properties = getToolProperties(tool);
+
+    expect(getActionEnum(properties)).toContain("download-file");
+    expect(properties.fileId).toMatchObject({ type: "string" });
+  });
 });
 
 describe("message tool description", () => {
diff --git a/src/agents/tools/message-tool.ts b/src/agents/tools/message-tool.ts
index 77f507aac67..f1e90691ebc 100644
--- a/src/agents/tools/message-tool.ts
+++ b/src/agents/tools/message-tool.ts
@@ -281,6 +281,7 @@ function buildChannelTargetSchema() {
 
 function buildStickerSchema() {
   return {
+    fileId: Type.Optional(Type.String()),
     emojiName: Type.Optional(Type.String()),
     stickerId: Type.Optional(Type.Array(Type.String())),
     stickerName: Type.Optional(Type.String()),