diff --git a/packages/web/src/lib/server/events.test.ts b/packages/web/src/lib/server/events.test.ts
index 33f9842..9cef457 100644
--- a/packages/web/src/lib/server/events.test.ts
+++ b/packages/web/src/lib/server/events.test.ts
@@ -1,5 +1,33 @@
 import { describe, expect, it } from 'vitest'
-import { deriveFields } from './events'
+import { deriveFields, truncateToolResponse } from './events'
+
+
+describe('truncateToolResponse', () => {
+  it('returns undefined when input is undefined', () => {
+    expect(truncateToolResponse(undefined)).toBeUndefined()
+  })
+
+  it('returns undefined when input is empty string', () => {
+    expect(truncateToolResponse('')).toBeUndefined()
+  })
+
+  it('returns original string when length is exactly 2000', () => {
+    const str = 'a'.repeat(2000)
+    expect(truncateToolResponse(str)).toBe(str)
+  })
+
+  it('returns original string when length is less than 2000', () => {
+    const str = 'hello world'
+    expect(truncateToolResponse(str)).toBe(str)
+  })
+
+  it('truncates string to exactly 2000 characters when length is greater than 2000', () => {
+    const longStr = 'a'.repeat(2500)
+    const result = truncateToolResponse(longStr)
+    expect(result).toHaveLength(2000)
+    expect(result).toBe('a'.repeat(2000))
+  })
+})
 
 describe('deriveFields', () => {
   it('marks normalized slash commands as skill calls', () => {
diff --git a/pr_desc.md b/pr_desc.md
new file mode 100644
index 0000000..a825dcb
--- /dev/null
+++ b/pr_desc.md
@@ -0,0 +1,10 @@
+🎯 **What:** Adds unit tests for the previously untested `truncateToolResponse` function in `packages/web/src/lib/server/events.ts`. This closes a testing gap for a small, pure string manipulation function.
+
+📊 **Coverage:** Covered the following scenarios:
+- Undefined input (returns undefined)
+- Empty string input (returns undefined)
+- String length exactly 2000 (returns original string)
+- String length < 2000 (returns original string)
+- String length > 2000 (returns truncated string of exactly 2000 characters)
+
+✨ **Result:** Improved test coverage and reliability. Future refactors around payload truncations will be safe.