fix: Update agent_card_builder to follow grammar rules

Merge https://github.com/google/adk-python/pull/2226

Fixes #2223

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/2226 from holtskinner:a2a-fixes ff556224e4071a8287a9ced19f645f0edd9916ef
PiperOrigin-RevId: 788512608

src/google/adk/a2a/utils/agent_card_builder.py

@@ -224,7 +224,7 @@ def _build_code_executor_skill(agent: LlmAgent) -> AgentSkill:
   return AgentSkill(
       id=f'{agent.name}-code-executor',
       name='code-execution',
-      description='Can execute codes',
+      description='Can execute code',
       examples=None,
       input_modes=None,
       output_modes=None,
@@ -359,11 +359,29 @@ def _build_llm_agent_description_with_instructions(agent: LlmAgent) -> str:
 
 
 def _replace_pronouns(text: str) -> str:
-  """Replace pronouns in text for agent description (you -> I, your -> my, etc.)."""
-  pronoun_map = {'you': 'I', 'your': 'my', 'yours': 'mine'}
+  """Replace pronouns and conjugate common verbs for agent description.
+  (e.g., "You are" -> "I am", "your" -> "my").
+  """
+  pronoun_map = {
+      # Longer phrases with verb conjugations
+      'you are': 'I am',
+      'you were': 'I was',
+      "you're": 'I am',
+      "you've": 'I have',
+      # Standalone pronouns
+      'yours': 'mine',
+      'your': 'my',
+      'you': 'I',
+  }
+
+  # Sort keys by length (descending) to ensure longer phrases are matched first.
+  # This prevents "you" in "you are" from being replaced on its own.
+  sorted_keys = sorted(pronoun_map.keys(), key=len, reverse=True)
+
+  pattern = r'\b(' + '|'.join(re.escape(key) for key in sorted_keys) + r')\b'
 
   return re.sub(
-      r'\b(you|your|yours)\b',
+      pattern,
       lambda match: pronoun_map[match.group(1).lower()],
       text,
       flags=re.IGNORECASE,

tests/unittests/a2a/utils/test_agent_card_builder.py

@@ -403,6 +403,17 @@ class TestHelperFunctions:
     # Assert
     assert result == "youth, yourself, yourname"  # No changes
 
+  def test_replace_pronouns_phrases(self):
+    """Test _replace_pronouns with phrases that should be replaced."""
+    # Arrange
+    text = "You are a helpful chatbot"
+
+    # Act
+    result = _replace_pronouns(text)
+
+    # Assert
+    assert result == "I am a helpful chatbot"
+
   def test_get_default_description_llm_agent(self):
     """Test _get_default_description for LlmAgent."""
     # Arrange