diff --git a/packages/tools/src/openai/tools.ts b/packages/tools/src/openai/tools.ts
index 5069a615..9bc593b0 100644
--- a/packages/tools/src/openai/tools.ts
+++ b/packages/tools/src/openai/tools.ts
@@ -458,8 +458,18 @@ export function getToolDefinitions(): OpenAI.Chat.Completions.ChatCompletionTool
 }
 
 function parseToolArguments(argumentsJson: string) {
+	// OpenAI sends "" for tools called with no arguments.
+	const source = argumentsJson?.trim() || "{}"
+
 	try {
-		return { success: true as const, value: JSON.parse(argumentsJson) }
+		const value = JSON.parse(source)
+
+		// "null", "5" and "[]" parse but would throw when destructured.
+		if (typeof value !== "object" || value === null || Array.isArray(value)) {
+			return { success: false as const }
+		}
+
+		return { success: true as const, value }
 	} catch {
 		return { success: false as const }
 	}
diff --git a/packages/tools/src/tool-operations.test.ts b/packages/tools/src/tool-operations.test.ts
index 1ec5c0ea..0283fcc3 100644
--- a/packages/tools/src/tool-operations.test.ts
+++ b/packages/tools/src/tool-operations.test.ts
@@ -341,6 +341,87 @@ describe("memoryForget", () => {
 	})
 })
 
+describe("openai executeToolCall argument parsing", () => {
+	type ExecutorToolCall = Parameters<
+		ReturnType<typeof openAi.createToolCallExecutor>
+	>[0]
+
+	function toolCall(name: string, args: string) {
+		return {
+			id: "call_1",
+			type: "function",
+			function: { name, arguments: args },
+		} as ExecutorToolCall
+	}
+
+	// getProfile, documentList and memoryForget declare `required: []`, so the model
+	// is allowed to call them with no arguments. OpenAI serialises that as "".
+	it.each([
+		"",
+		"   ",
+	])("runs a zero-argument tool when arguments are %p", async (args) => {
+		const execute = openAi.createToolCallExecutor(API_KEY, {
+			namespace: "user_1",
+		})
+
+		const result = JSON.parse(await execute(toolCall("getProfile", args)))
+
+		expect(result.success).toBe(true)
+		expect(sdk.profile).toHaveBeenCalledTimes(1)
+		expect(sdk.profile.mock.calls[0]?.[0]).toBe("user_1")
+	})
+
+	// These parse cleanly, so the JSON guard lets them through to a destructuring
+	// parameter that rejects — the throw the guard exists to contain.
+	it.each([
+		"null",
+		"5",
+		"[]",
+		'"text"',
+	])("rejects non-object arguments %p as a tool result rather than throwing", async (args) => {
+		const execute = openAi.createToolCallExecutor(API_KEY)
+
+		const result = JSON.parse(await execute(toolCall("getProfile", args)))
+
+		expect(result.success).toBe(false)
+		expect(result.error).toMatch(/Invalid JSON arguments for getProfile/)
+		expect(sdk.profile).not.toHaveBeenCalled()
+	})
+
+	it("still reports malformed JSON as a tool error", async () => {
+		const execute = openAi.createToolCallExecutor(API_KEY)
+
+		const result = JSON.parse(
+			await execute(toolCall("searchMemories", "{not json")),
+		)
+
+		expect(result.success).toBe(false)
+		expect(result.error).toMatch(/Invalid JSON arguments for searchMemories/)
+		expect(sdk.search).not.toHaveBeenCalled()
+	})
+
+	it("still passes well-formed arguments through", async () => {
+		const execute = openAi.createToolCallExecutor(API_KEY, {
+			namespace: "user_1",
+		})
+
+		const result = JSON.parse(
+			await execute(
+				toolCall(
+					"searchMemories",
+					JSON.stringify({ informationToGet: "tea", limit: 3 }),
+				),
+			),
+		)
+
+		expect(result.success).toBe(true)
+		expect(sdk.search).toHaveBeenCalledWith(
+			"user_1",
+			expect.objectContaining({ query: "tea", limit: 3 }),
+		)
+	})
+})
+
 describe("ClaudeMemoryTool", () => {
 	const FILE_PATH = "/memories/prefs.txt"
 	const FILE_ID = "memories_prefs_txt"