diff --git a/CHANGELOG.md b/CHANGELOG.md
index a134359f5..d34c7d651 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -58,6 +58,7 @@ Status: beta.
 - iMessage: normalize messaging targets. (#1708)
 - Signal: fix reactions and add configurable startup timeout. (#1651, #1677)
 - Matrix: decrypt E2EE media with size guard. (#1744)
+- Message tool: disable cross-context origin marker by default; set `tools.message.crossContext.marker.enabled: true` to restore. (#1782)
 
 
 ## 2026.1.24
diff --git a/src/config/schema.ts b/src/config/schema.ts
index 28c994f3d..8ff91ca19 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -428,7 +428,7 @@ const FIELD_HELP: Record<string, string> = {
   "tools.message.crossContext.allowAcrossProviders":
     "Allow sends across different providers (default: false).",
   "tools.message.crossContext.marker.enabled":
-    "Add a visible origin marker when sending cross-context (default: true).",
+    "Add a visible origin marker when sending cross-context (default: false).",
   "tools.message.crossContext.marker.prefix":
     'Text prefix for cross-context markers (supports "{channel}").',
   "tools.message.crossContext.marker.suffix":
diff --git a/src/config/types.tools.ts b/src/config/types.tools.ts
index db32cb59d..4cc681d27 100644
--- a/src/config/types.tools.ts
+++ b/src/config/types.tools.ts
@@ -403,7 +403,7 @@ export type ToolsConfig = {
       allowAcrossProviders?: boolean;
       /** Cross-context marker configuration. */
       marker?: {
-        /** Enable origin markers for cross-context sends (default: true). */
+        /** Enable origin markers for cross-context sends (default: false). */
         enabled?: boolean;
         /** Text prefix template, supports {channel}. */
         prefix?: string;
diff --git a/src/infra/outbound/outbound-policy.test.ts b/src/infra/outbound/outbound-policy.test.ts
index f798d7e9b..d999e783d 100644
--- a/src/infra/outbound/outbound-policy.test.ts
+++ b/src/infra/outbound/outbound-policy.test.ts
@@ -72,8 +72,12 @@ describe("outbound policy", () => {
   });
 
   it("uses embeds when available and preferred", async () => {
+    const cfg = {
+      ...discordConfig,
+      tools: { message: { crossContext: { marker: { enabled: true } } } },
+    } as MoltbotConfig;
     const decoration = await buildCrossContextDecoration({
-      cfg: discordConfig,
+      cfg,
       channel: "discord",
       target: "123",
       toolContext: { currentChannelId: "C12345678", currentChannelProvider: "discord" },
diff --git a/src/infra/outbound/outbound-policy.ts b/src/infra/outbound/outbound-policy.ts
index 9b3470949..74fb9d84b 100644
--- a/src/infra/outbound/outbound-policy.ts
+++ b/src/infra/outbound/outbound-policy.ts
@@ -124,7 +124,7 @@ export async function buildCrossContextDecoration(params: {
   if (!isCrossContextTarget(params)) return null;
 
   const markerConfig = params.cfg.tools?.message?.crossContext?.marker;
-  if (markerConfig?.enabled === false) return null;
+  if (markerConfig?.enabled !== true) return null;
 
   const currentName =
     (await lookupDirectoryDisplay({