diff --git a/docs/tools/subagents.md b/docs/tools/subagents.md
index c1d4ce4d9..d17191960 100644
--- a/docs/tools/subagents.md
+++ b/docs/tools/subagents.md
@@ -27,6 +27,7 @@ Tool params:
 - `label?` (optional)
 - `agentId?` (optional; spawn under another agent id if allowed)
 - `model?` (optional; overrides the sub-agent model; invalid values are skipped and the sub-agent runs on the default model with a warning in the tool result)
+- `thinking?` (optional; overrides thinking level for the sub-agent run)
 - `runTimeoutSeconds?` (default `0`; when set, the sub-agent run is aborted after N seconds)
 - `cleanup?` (`delete|keep`, default `keep`)
 
diff --git a/src/agents/clawdbot-tools.sessions.test.ts b/src/agents/clawdbot-tools.sessions.test.ts
index d795f463b..3f465a867 100644
--- a/src/agents/clawdbot-tools.sessions.test.ts
+++ b/src/agents/clawdbot-tools.sessions.test.ts
@@ -54,6 +54,7 @@ describe("sessions tools", () => {
     expect(schemaProp("sessions_list", "activeMinutes").type).toBe("number");
     expect(schemaProp("sessions_list", "messageLimit").type).toBe("number");
     expect(schemaProp("sessions_send", "timeoutSeconds").type).toBe("number");
+    expect(schemaProp("sessions_spawn", "thinking").type).toBe("string");
     expect(schemaProp("sessions_spawn", "runTimeoutSeconds").type).toBe("number");
     expect(schemaProp("sessions_spawn", "timeoutSeconds").type).toBe("number");
   });
diff --git a/src/agents/clawdbot-tools.subagents.sessions-spawn-applies-model-child-session.test.ts b/src/agents/clawdbot-tools.subagents.sessions-spawn-applies-model-child-session.test.ts
index abc420f7e..2eea23bf0 100644
--- a/src/agents/clawdbot-tools.subagents.sessions-spawn-applies-model-child-session.test.ts
+++ b/src/agents/clawdbot-tools.subagents.sessions-spawn-applies-model-child-session.test.ts
@@ -92,6 +92,68 @@ describe("clawdbot-tools: subagents", () => {
       model: "claude-haiku-4-5",
     });
   });
+
+  it("sessions_spawn forwards thinking overrides to the agent run", async () => {
+    resetSubagentRegistryForTests();
+    callGatewayMock.mockReset();
+    const calls: Array<{ method?: string; params?: unknown }> = [];
+
+    callGatewayMock.mockImplementation(async (opts: unknown) => {
+      const request = opts as { method?: string; params?: unknown };
+      calls.push(request);
+      if (request.method === "agent") {
+        return { runId: "run-thinking", status: "accepted" };
+      }
+      return {};
+    });
+
+    const tool = createClawdbotTools({
+      agentSessionKey: "discord:group:req",
+      agentChannel: "discord",
+    }).find((candidate) => candidate.name === "sessions_spawn");
+    if (!tool) throw new Error("missing sessions_spawn tool");
+
+    const result = await tool.execute("call-thinking", {
+      task: "do thing",
+      thinking: "high",
+    });
+    expect(result.details).toMatchObject({
+      status: "accepted",
+    });
+
+    const agentCall = calls.find((call) => call.method === "agent");
+    expect(agentCall?.params).toMatchObject({
+      thinking: "high",
+    });
+  });
+
+  it("sessions_spawn rejects invalid thinking levels", async () => {
+    resetSubagentRegistryForTests();
+    callGatewayMock.mockReset();
+    const calls: Array<{ method?: string }> = [];
+
+    callGatewayMock.mockImplementation(async (opts: unknown) => {
+      const request = opts as { method?: string };
+      calls.push(request);
+      return {};
+    });
+
+    const tool = createClawdbotTools({
+      agentSessionKey: "discord:group:req",
+      agentChannel: "discord",
+    }).find((candidate) => candidate.name === "sessions_spawn");
+    if (!tool) throw new Error("missing sessions_spawn tool");
+
+    const result = await tool.execute("call-thinking-invalid", {
+      task: "do thing",
+      thinking: "banana",
+    });
+    expect(result.details).toMatchObject({
+      status: "error",
+    });
+    expect(String(result.details?.error)).toMatch(/Invalid thinking level/i);
+    expect(calls).toHaveLength(0);
+  });
   it("sessions_spawn applies default subagent model from defaults config", async () => {
     resetSubagentRegistryForTests();
     callGatewayMock.mockReset();
diff --git a/src/agents/tool-display.json b/src/agents/tool-display.json
index 79358640e..603c51e3b 100644
--- a/src/agents/tool-display.json
+++ b/src/agents/tool-display.json
@@ -266,7 +266,7 @@
     "sessions_spawn": {
       "emoji": "🧑‍🔧",
       "title": "Sub-agent",
-      "detailKeys": ["label", "agentId", "runTimeoutSeconds", "cleanup"]
+      "detailKeys": ["label", "agentId", "thinking", "runTimeoutSeconds", "cleanup"]
     },
     "session_status": {
       "emoji": "📊",
diff --git a/src/agents/tools/sessions-spawn-tool.ts b/src/agents/tools/sessions-spawn-tool.ts
index e743c07d1..e9b8e0764 100644
--- a/src/agents/tools/sessions-spawn-tool.ts
+++ b/src/agents/tools/sessions-spawn-tool.ts
@@ -2,6 +2,7 @@ import crypto from "node:crypto";
 
 import { Type } from "@sinclair/typebox";
 
+import { formatThinkingLevels, normalizeThinkLevel } from "../../auto-reply/thinking.js";
 import { loadConfig } from "../../config/config.js";
 import { callGateway } from "../../gateway/call.js";
 import {
@@ -29,12 +30,22 @@ const SessionsSpawnToolSchema = Type.Object({
   label: Type.Optional(Type.String()),
   agentId: Type.Optional(Type.String()),
   model: Type.Optional(Type.String()),
+  thinking: Type.Optional(Type.String()),
   runTimeoutSeconds: Type.Optional(Type.Number({ minimum: 0 })),
   // Back-compat alias. Prefer runTimeoutSeconds.
   timeoutSeconds: Type.Optional(Type.Number({ minimum: 0 })),
   cleanup: optionalStringEnum(["delete", "keep"] as const),
 });
 
+function splitModelRef(ref?: string) {
+  if (!ref) return { provider: undefined, model: undefined };
+  const trimmed = ref.trim();
+  if (!trimmed) return { provider: undefined, model: undefined };
+  const [provider, model] = trimmed.split("/", 2);
+  if (model) return { provider, model };
+  return { provider: undefined, model: trimmed };
+}
+
 function normalizeModelSelection(value: unknown): string | undefined {
   if (typeof value === "string") {
     const trimmed = value.trim();
@@ -64,6 +75,7 @@ export function createSessionsSpawnTool(opts?: {
       const label = typeof params.label === "string" ? params.label.trim() : "";
       const requestedAgentId = readStringParam(params, "agentId");
       const modelOverride = readStringParam(params, "model");
+      const thinkingOverrideRaw = readStringParam(params, "thinking");
       const cleanup =
         params.cleanup === "keep" || params.cleanup === "delete"
           ? (params.cleanup as "keep" | "delete")
@@ -143,6 +155,19 @@ export function createSessionsSpawnTool(opts?: {
         normalizeModelSelection(modelOverride) ??
         normalizeModelSelection(targetAgentConfig?.subagents?.model) ??
         normalizeModelSelection(cfg.agents?.defaults?.subagents?.model);
+      let thinkingOverride: string | undefined;
+      if (thinkingOverrideRaw) {
+        const normalized = normalizeThinkLevel(thinkingOverrideRaw);
+        if (!normalized) {
+          const { provider, model } = splitModelRef(resolvedModel);
+          const hint = formatThinkingLevels(provider, model);
+          return jsonResult({
+            status: "error",
+            error: `Invalid thinking level "${thinkingOverrideRaw}". Use one of: ${hint}.`,
+          });
+        }
+        thinkingOverride = normalized;
+      }
       if (resolvedModel) {
         try {
           await callGateway({
@@ -187,6 +212,7 @@ export function createSessionsSpawnTool(opts?: {
             deliver: false,
             lane: AGENT_LANE_SUBAGENT,
             extraSystemPrompt: childSystemPrompt,
+            thinking: thinkingOverride,
             timeout: runTimeoutSeconds > 0 ? runTimeoutSeconds : undefined,
             label: label || undefined,
             spawnedBy: shouldPatchSpawnedBy ? requesterInternalKey : undefined,