diff --git a/.env.example b/.env.example
index 62618cc..fc2e777 100644
--- a/.env.example
+++ b/.env.example
@@ -57,3 +57,5 @@ LLM_API_KEY=
 LLM_MODEL=llama3.2
 # IANA timezone for assistant relative dates ("Thursday at 2"). Falls back to TZ, then America/Chicago.
 HOUSEHOLD_TIMEZONE=America/Chicago
+# Optional override for agent tool → /api/v1 self-calls (defaults to http://127.0.0.1:$PORT).
+# INTERNAL_API_BASE_URL=http://127.0.0.1:3000
diff --git a/src/modules/agent/server/run.ts b/src/modules/agent/server/run.ts
index 27665e8..0b4ef12 100644
--- a/src/modules/agent/server/run.ts
+++ b/src/modules/agent/server/run.ts
@@ -160,8 +160,20 @@ export async function runAgentChat(options: {
 
       try {
         result = await executeTool(toolCall.function.name, toolCall.function.arguments);
-        const parsed = JSON.parse(result) as { status?: number };
+        const parsed = JSON.parse(result) as { status?: number; body?: unknown };
         status = typeof parsed.status === "number" ? parsed.status : 200;
+        if (status >= 400) {
+          logger.warn(
+            {
+              msg: "agent.chat.tool_error",
+              round,
+              name: toolCall.function.name,
+              status,
+              body: parsed.body,
+            },
+            "agent tool returned error",
+          );
+        }
       } catch (err) {
         status = 500;
         result = JSON.stringify({
diff --git a/src/modules/agent/tool-executor.ts b/src/modules/agent/tool-executor.ts
index e8a1c4c..40065f0 100644
--- a/src/modules/agent/tool-executor.ts
+++ b/src/modules/agent/tool-executor.ts
@@ -1,3 +1,5 @@
+import logger from "@/lib/logger";
+
 type ApiCallResult = {
   status: number;
   body: unknown;
@@ -5,8 +7,22 @@ type ApiCallResult = {
 
 export type ToolExecutor = (name: string, argsJson: string) => Promise<string>;
 
+/** Loopback base for in-process tool → /api/v1 calls. Avoids hairpinning to the public URL. */
+export function resolveInternalApiBase(request: Request): string {
+  const configured = process.env.INTERNAL_API_BASE_URL?.trim();
+  if (configured) return configured.replace(/\/$/, "");
+
+  const port = process.env.PORT?.trim() || "3000";
+  const requestUrl = new URL(request.url);
+  if (requestUrl.hostname === "localhost" || requestUrl.hostname === "127.0.0.1") {
+    return requestUrl.origin;
+  }
+
+  return `http://127.0.0.1:${port}`;
+}
+
 export function createApiToolExecutor(request: Request): ToolExecutor {
-  const origin = new URL(request.url).origin;
+  const origin = resolveInternalApiBase(request);
 
   return async (name: string, argsJson: string) => {
     const args = parseArgs(argsJson);
@@ -522,14 +538,30 @@ async function callApi(
   path: string,
   body?: Record<string, unknown>,
 ): Promise<ApiCallResult> {
-  const response = await fetch(`${origin}${path}`, {
-    method,
-    headers: {
-      "Content-Type": "application/json",
-      cookie: request.headers.get("cookie") ?? "",
-    },
-    body: body !== undefined ? JSON.stringify(body) : undefined,
-  });
+  const url = `${origin}${path}`;
+  const headers: Record<string, string> = {
+    "Content-Type": "application/json",
+  };
+  const cookie = request.headers.get("cookie");
+  if (cookie) headers.cookie = cookie;
+  const authorization = request.headers.get("authorization");
+  if (authorization) headers.authorization = authorization;
+
+  let response: Response;
+  try {
+    response = await fetch(url, {
+      method,
+      headers,
+      body: body !== undefined ? JSON.stringify(body) : undefined,
+    });
+  } catch (err) {
+    const message = err instanceof Error ? err.message : "fetch failed";
+    logger.error(
+      { msg: "agent.tool.fetch_failed", method, url, error: message },
+      "agent tool internal fetch failed",
+    );
+    return { status: 502, body: { error: `Internal API unreachable: ${message}`, url } };
+  }
 
   const text = await response.text();
   let parsed: unknown = null;
@@ -541,5 +573,12 @@ async function callApi(
     }
   }
 
+  if (response.status >= 400) {
+    logger.warn(
+      { msg: "agent.tool.api_error", method, url, status: response.status, body: parsed },
+      "agent tool API error",
+    );
+  }
+
   return { status: response.status, body: parsed };
 }
diff --git a/tests/unit/agent-tools-runtime.test.ts b/tests/unit/agent-tools-runtime.test.ts
index 82437b1..fa138b9 100644
--- a/tests/unit/agent-tools-runtime.test.ts
+++ b/tests/unit/agent-tools-runtime.test.ts
@@ -1,7 +1,10 @@
 import assert from "node:assert/strict";
 import { describe, it } from "node:test";
 import { appendAgentRuntimeContext, resolveHouseholdTimezone } from "../../src/modules/agent/tools";
-import { createApiToolExecutor } from "../../src/modules/agent/tool-executor";
+import {
+  createApiToolExecutor,
+  resolveInternalApiBase,
+} from "../../src/modules/agent/tool-executor";
 
 describe("appendAgentRuntimeContext", () => {
   it("appends current time and timezone to the prompt", () => {
@@ -38,6 +41,34 @@ describe("resolveHouseholdTimezone", () => {
   });
 });
 
+describe("resolveInternalApiBase", () => {
+  it("uses loopback instead of the public request origin", () => {
+    const original = process.env.INTERNAL_API_BASE_URL;
+    const originalPort = process.env.PORT;
+    delete process.env.INTERNAL_API_BASE_URL;
+    process.env.PORT = "3000";
+
+    const base = resolveInternalApiBase(new Request("https://fam.ginnoir.com/api/agent/chat"));
+    assert.equal(base, "http://127.0.0.1:3000");
+
+    if (original === undefined) delete process.env.INTERNAL_API_BASE_URL;
+    else process.env.INTERNAL_API_BASE_URL = original;
+    if (originalPort === undefined) delete process.env.PORT;
+    else process.env.PORT = originalPort;
+  });
+
+  it("honors INTERNAL_API_BASE_URL when set", () => {
+    const original = process.env.INTERNAL_API_BASE_URL;
+    process.env.INTERNAL_API_BASE_URL = "http://127.0.0.1:3010/";
+
+    const base = resolveInternalApiBase(new Request("https://fam.ginnoir.com/api/agent/chat"));
+    assert.equal(base, "http://127.0.0.1:3010");
+
+    if (original === undefined) delete process.env.INTERNAL_API_BASE_URL;
+    else process.env.INTERNAL_API_BASE_URL = original;
+  });
+});
+
 describe("create_event calendar resolution", () => {
   it("uses the first calendar when calendarId and calendarName are omitted", async () => {
     const originalFetch = globalThis.fetch;
@@ -45,13 +76,13 @@ describe("create_event calendar resolution", () => {
 
     globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit) => {
       const url = String(input);
-      if (url.endsWith("/api/v1/calendars") && (!init?.method || init.method === "GET")) {
+      if (url.includes("/api/v1/calendars") && (!init?.method || init.method === "GET")) {
         return Response.json([
           { id: "cal-1", name: "Family" },
           { id: "cal-2", name: "Work" },
         ]);
       }
-      if (url.endsWith("/api/v1/events") && init?.method === "POST") {
+      if (url.includes("/api/v1/events") && init?.method === "POST") {
         const body = JSON.parse(String(init.body));
         posts.push({ path: url, body });
         return Response.json({ id: "evt-1", ...body }, { status: 201 });
@@ -59,7 +90,11 @@ describe("create_event calendar resolution", () => {
       return new Response("not found", { status: 404 });
     }) as typeof fetch;
 
-    const execute = createApiToolExecutor(new Request("http://localhost:3000/api/agent/chat"));
+    const execute = createApiToolExecutor(
+      new Request("https://fam.ginnoir.com/api/agent/chat", {
+        headers: { cookie: "authjs.session-token=test" },
+      }),
+    );
     const result = JSON.parse(
       await execute(
         "create_event",
@@ -74,6 +109,7 @@ describe("create_event calendar resolution", () => {
     assert.equal(result.status, 201);
     assert.equal(result.body.calendarId, "cal-1");
     assert.equal(posts.length, 1);
+    assert.match(posts[0]!.path, /^http:\/\/127\.0\.0\.1:3000\/api\/v1\/events/);
 
     globalThis.fetch = originalFetch;
   });
@@ -83,13 +119,13 @@ describe("create_event calendar resolution", () => {
 
     globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit) => {
       const url = String(input);
-      if (url.endsWith("/api/v1/calendars") && (!init?.method || init.method === "GET")) {
+      if (url.includes("/api/v1/calendars") && (!init?.method || init.method === "GET")) {
         return Response.json([
           { id: "cal-1", name: "Family" },
           { id: "cal-2", name: "Work" },
         ]);
       }
-      if (url.endsWith("/api/v1/events") && init?.method === "POST") {
+      if (url.includes("/api/v1/events") && init?.method === "POST") {
         const body = JSON.parse(String(init.body));
         return Response.json({ id: "evt-1", ...body }, { status: 201 });
       }
@@ -114,4 +150,22 @@ describe("create_event calendar resolution", () => {
 
     globalThis.fetch = originalFetch;
   });
+
+  it("returns a clear error when the internal API is unreachable", async () => {
+    const originalFetch = globalThis.fetch;
+    globalThis.fetch = (async () => {
+      throw new TypeError("fetch failed");
+    }) as typeof fetch;
+
+    const execute = createApiToolExecutor(new Request("https://fam.ginnoir.com/api/agent/chat"));
+    const result = JSON.parse(await execute("list_calendars", "{}")) as {
+      status: number;
+      body: { error?: string };
+    };
+
+    assert.equal(result.status, 502);
+    assert.match(String(result.body.error), /unreachable/i);
+
+    globalThis.fetch = originalFetch;
+  });
 });