diff --git a/docs/tools/code-mode/guest-api.md b/docs/tools/code-mode/guest-api.md
index 19d7e9d9c1d8..08683814641c 100644
--- a/docs/tools/code-mode/guest-api.md
+++ b/docs/tools/code-mode/guest-api.md
@@ -215,9 +215,12 @@ const hits = await search({ query: "OpenClaw code mode" });
 ```
 
 Calling a native global or native catalog handle returns the normal tool's JSON `details`
-value directly. MCP handles retain the native MCP result (`content`, optional
-`structuredContent`, and optional `isError`). Exact catalog ids and raw `{ tool, result }` envelopes are not
-guest-visible.
+value directly. When a tool marks its result `isError: true` and its details carry no
+non-empty `message` or `error` string, the value includes the tool's text content
+as `message`, so guest code and the model can see why the call failed. MCP handles
+retain the native MCP result (`content`, optional `structuredContent`, and
+optional `isError`). Exact catalog ids and raw `{ tool, result }` envelopes are
+not guest-visible.
 
 The `ls`, `find`, and `grep` tools include their bounded listing or search text
 in `content`, including empty-result messages and truncation notices. Directory
diff --git a/src/agents/code-mode-bridge.ts b/src/agents/code-mode-bridge.ts
index d64f4410d094..a29d18ff20f6 100644
--- a/src/agents/code-mode-bridge.ts
+++ b/src/agents/code-mode-bridge.ts
@@ -339,16 +339,12 @@ export async function runBridgeRequest(params: {
             yieldMs: Math.max(1, Math.min(1_000, Math.floor(params.remainingMs / 4))),
           };
         }
-        const called = await params.runtime.callExactId(binding.id, input, {
+        value = await params.runtime.callExactValue(binding.id, input, {
           recoverySurface: "catalog",
           parentToolCallId: params.parentToolCallId,
           signal: params.signal,
           onUpdate: params.onUpdate,
         });
-        value =
-          isRecord(called.result) && "details" in called.result
-            ? called.result.details
-            : called.result;
         break;
       }
       case "nodes": {
diff --git a/src/agents/code-mode.contracts.test.ts b/src/agents/code-mode.contracts.test.ts
index 9d9b3d7df133..1c55e96a1387 100644
--- a/src/agents/code-mode.contracts.test.ts
+++ b/src/agents/code-mode.contracts.test.ts
@@ -124,6 +124,36 @@ it("allows omitted native empty inputs but preserves required fields", async ()
   expect(required.execute).toHaveBeenCalledOnce();
 });
 
+it("keeps an explicit tool error's text when its details carry no message", async () => {
+  const h = createCodeModeHarness();
+  const reason = "Start the Gateway with visitor-access enabled before managing visitors.";
+  const errorTool = (name: string, text: string, details: unknown) =>
+    pluginToolWithExecute(name, "Fail", async () => ({
+      content: [{ type: "text" as const, text }],
+      details,
+      isError: true,
+    }));
+  const tools = [
+    errorTool("flag_only", reason, { error: true }),
+    errorTool("no_details", "Gateway unavailable.", undefined),
+    errorTool("blank_message", "Visitor store is locked.", { error: true, message: " " }),
+    errorTool("structured", "Rendered failure.", { status: "failed", error: "structured" }),
+  ];
+  applyCodeModeCatalog({ ...h.ctx, tools: [...h.tools, ...tools] });
+  const result = resultDetails(
+    await expectDefined(h.tools[0], "exec").execute("tool-error-text", {
+      code: "return [await flag_only(), await no_details(), await blank_message(), await structured()];",
+    }),
+  );
+  expect(result.status, JSON.stringify(result)).toBe("completed");
+  expect(result.value).toEqual([
+    { error: true, message: reason },
+    { message: "Gateway unavailable." },
+    { error: true, message: "Visitor store is locked." },
+    { status: "failed", error: "structured" },
+  ]);
+});
+
 it("merges actual root and multiple server files without skipping declaration errors", () => {
   const files = createMcpApiVirtualFiles(
     ["alpha", "beta", "index"].map((identifier) => ({
diff --git a/src/agents/tool-search-runtime.ts b/src/agents/tool-search-runtime.ts
index fecb7fb763bc..536f4721a85b 100644
--- a/src/agents/tool-search-runtime.ts
+++ b/src/agents/tool-search-runtime.ts
@@ -9,6 +9,7 @@ import {
 } from "./agent-tools.before-tool-call.js";
 import { runWithToolExecutionValidation } from "./agent-tools.execution-validation.js";
 import { getChannelAgentToolMeta } from "./channel-tool-metadata.js";
+import { collectTextContentBlocks } from "./content-blocks.js";
 import { setMcpCodeModeGuestResultFromAgentResult } from "./mcp-content.js";
 import { captureAgentPluginRuntimeRefresh } from "./plugin-runtime-refresh.js";
 import type { AgentToolResult } from "./runtime/index.js";
@@ -65,6 +66,11 @@ import type {
 } from "./tool-search-types.js";
 import { textResult, ToolInputError } from "./tools/common.js";
 
+type ToolSearchExactCallOptions = Pick<
+  ToolSearchCallOptions,
+  "parentToolCallId" | "signal" | "onUpdate" | "recoverySurface" | "mcpNamespaceGuest"
+>;
+
 function describeEntry(entry: ToolSearchCatalogEntry) {
   return {
     ...compactToolSearchCatalogEntry(entry),
@@ -412,14 +418,7 @@ export class ToolSearchRuntime {
     );
   };
 
-  callExactId = async (
-    id: string,
-    input?: unknown,
-    options?: Pick<
-      ToolSearchCallOptions,
-      "parentToolCallId" | "signal" | "onUpdate" | "recoverySurface" | "mcpNamespaceGuest"
-    >,
-  ) => {
+  callExactId = async (id: string, input?: unknown, options?: ToolSearchExactCallOptions) => {
     const catalog = resolveCatalog(this.ctx);
     return await this.callEntry(
       findEntryByExactId(catalog, id, { ...options, codeModeSkills: this.ctx.codeModeSkills }),
@@ -429,7 +428,10 @@ export class ToolSearchRuntime {
   };
 
   callValue = async (id: string, input?: unknown, options?: ToolSearchCallOptions) =>
-    unwrapToolResultValue((await this.call(id, input, options)).result);
+    projectToolResultValue((await this.call(id, input, options)).result);
+
+  callExactValue = async (id: string, input?: unknown, options?: ToolSearchExactCallOptions) =>
+    projectToolResultValue((await this.callExactId(id, input, options)).result);
 
   observeNetworkContent(parentToolCallId: string): void {
     const state = this.networkInvocations.get(parentToolCallId) ?? { active: 0, observed: false };
@@ -699,3 +701,36 @@ export function formatToolSearchControlError(
 function unwrapToolResultValue(result: AgentToolResult<unknown>): unknown {
   return isRecord(result) && "details" in result ? result.details : result;
 }
+
+/**
+ * Project a target result into the value Code Mode guests receive. Output
+ * contracts validate the raw details; only the guest value gains error text.
+ */
+function projectToolResultValue(result: AgentToolResult<unknown>): unknown {
+  if (!isRecord(result) || !("details" in result)) {
+    return result;
+  }
+  const { details } = result;
+  // An explicit error can explain itself only in model-facing text; keep that reason.
+  if (result.isError !== true || hasErrorMessage(details)) {
+    return details;
+  }
+  const message = collectTextContentBlocks(result.content)
+    .map((text) => text.trim())
+    .filter(Boolean)
+    .join("\n");
+  if (!message) {
+    return details;
+  }
+  if (details === undefined || details === null) {
+    return { message };
+  }
+  return isRecord(details) ? { ...details, message } : details;
+}
+
+function hasErrorMessage(details: unknown): boolean {
+  return (
+    isRecord(details) &&
+    [details.message, details.error].some((value) => typeof value === "string" && value.trim())
+  );
+}