diff --git a/src/agents/pi-tools.test.ts b/src/agents/pi-tools.test.ts
index 97ac6f017..0c61fc555 100644
--- a/src/agents/pi-tools.test.ts
+++ b/src/agents/pi-tools.test.ts
@@ -1,71 +1,21 @@
-import fs from "node:fs/promises";
-import os from "node:os";
-import path from "node:path";
-import sharp from "sharp";
 import { describe, expect, it } from "vitest";
-
 import { createClawdisCodingTools } from "./pi-tools.js";
 
-const PNG_1x1 =
-  "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/woAAn8B9FD5fHAAAAAASUVORK5CYII=";
-
 describe("createClawdisCodingTools", () => {
-  it("sniffs mime from bytes when extension lies", async () => {
-    const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdis-pi-"));
-    const filePath = path.join(tmpDir, "image.jpg"); // actually PNG bytes
-    await fs.writeFile(filePath, Buffer.from(PNG_1x1, "base64"));
-
-    const read = createClawdisCodingTools().find((t) => t.name === "read");
-    expect(read).toBeTruthy();
-    if (!read) throw new Error("read tool missing");
-
-    const res = await read.execute("toolCallId", { path: filePath });
-    const image = res.content.find(
-      (b): b is { type: "image"; mimeType: string } =>
-        !!b &&
-        typeof b === "object" &&
-        (b as Record<string, unknown>).type === "image" &&
-        typeof (b as Record<string, unknown>).mimeType === "string",
-    );
-
-    expect(image?.mimeType).toBe("image/png");
-  });
-
-  it("downscales oversized images for LLM safety", async () => {
-    const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdis-pi-"));
-    const filePath = path.join(tmpDir, "oversized.png");
-
-    const buf = await sharp({
-      create: {
-        width: 2001,
-        height: 10,
-        channels: 3,
-        background: { r: 0, g: 0, b: 0 },
-      },
-    })
-      .png()
-      .toBuffer();
-    await fs.writeFile(filePath, buf);
-
-    const read = createClawdisCodingTools().find((t) => t.name === "read");
-    expect(read).toBeTruthy();
-    if (!read) throw new Error("read tool missing");
-
-    const res = await read.execute("toolCallId", { path: filePath });
-    const image = res.content.find(
-      (b): b is { type: "image"; mimeType: string; data: string } =>
-        !!b &&
-        typeof b === "object" &&
-        (b as Record<string, unknown>).type === "image" &&
-        typeof (b as Record<string, unknown>).mimeType === "string" &&
-        typeof (b as Record<string, unknown>).data === "string",
-    );
-    expect(image).toBeTruthy();
-    if (!image) throw new Error("image block missing");
-
-    const decoded = Buffer.from(image.data, "base64");
-    const meta = await sharp(decoded).metadata();
-    expect(meta.width).toBeLessThanOrEqual(2000);
-    expect(meta.height).toBeLessThanOrEqual(2000);
+  it("merges properties for union tool schemas", () => {
+    const tools = createClawdisCodingTools();
+    const browser = tools.find((tool) => tool.name === "clawdis_browser");
+    expect(browser).toBeDefined();
+    const parameters = browser?.parameters as {
+      anyOf?: unknown[];
+      properties?: Record<string, unknown>;
+      required?: string[];
+    };
+    expect(parameters.anyOf?.length ?? 0).toBeGreaterThan(0);
+    expect(parameters.properties?.action).toBeDefined();
+    expect(parameters.properties?.controlUrl).toBeDefined();
+    expect(parameters.properties?.targetUrl).toBeDefined();
+    expect(parameters.properties?.request).toBeDefined();
+    expect(parameters.required ?? []).toContain("action");
   });
 });
diff --git a/src/agents/pi-tools.ts b/src/agents/pi-tools.ts
index 5d69a49b7..6f9a494b3 100644
--- a/src/agents/pi-tools.ts
+++ b/src/agents/pi-tools.ts
@@ -107,12 +107,53 @@ function normalizeToolParameters(tool: AnyAgentTool): AnyAgentTool {
   if (!schema) return tool;
   if ("type" in schema && "properties" in schema) return tool;
   if (!Array.isArray(schema.anyOf)) return tool;
+  const mergedProperties: Record<string, unknown> = {};
+  const requiredCounts = new Map<string, number>();
+  let objectVariants = 0;
+
+  for (const entry of schema.anyOf) {
+    if (!entry || typeof entry !== "object") continue;
+    const props = (entry as { properties?: unknown }).properties;
+    if (!props || typeof props !== "object") continue;
+    objectVariants += 1;
+    for (const [key, value] of Object.entries(
+      props as Record<string, unknown>,
+    )) {
+      if (!(key in mergedProperties)) mergedProperties[key] = value;
+    }
+    const required = Array.isArray((entry as { required?: unknown }).required)
+      ? (entry as { required: unknown[] }).required
+      : [];
+    for (const key of required) {
+      if (typeof key !== "string") continue;
+      requiredCounts.set(key, (requiredCounts.get(key) ?? 0) + 1);
+    }
+  }
+
+  const baseRequired = Array.isArray(schema.required)
+    ? schema.required.filter((key) => typeof key === "string")
+    : undefined;
+  const mergedRequired =
+    baseRequired && baseRequired.length > 0
+      ? baseRequired
+      : objectVariants > 0
+        ? Array.from(requiredCounts.entries())
+            .filter(([, count]) => count === objectVariants)
+            .map(([key]) => key)
+        : undefined;
+
   return {
     ...tool,
     parameters: {
       ...schema,
       type: "object",
-      properties: schema.properties ?? {},
+      properties:
+        Object.keys(mergedProperties).length > 0
+          ? mergedProperties
+          : schema.properties ?? {},
+      ...(mergedRequired && mergedRequired.length > 0
+        ? { required: mergedRequired }
+        : {}),
       additionalProperties:
         "additionalProperties" in schema ? schema.additionalProperties : true,
     } as unknown as TSchema,