fix: improve PR description and title field descriptions for clarity

pr_agent/settings/pr_description_prompts.toml

@@ -52,8 +52,8 @@ class PRDescription(BaseModel):
 {%- if enable_semantic_files_types %}
     pr_files: List[FileDescription] = Field(max_items=20, description="a list of all the files that were changed in the PR, and summary of their changes. Each file must be analyzed regardless of change size.")
 {%- endif %}
-    description: str = Field(description="an informative and concise description of the PR. Use bullet points. Display first the most significant changes.")
-    title: str = Field(description="an informative title for the PR, describing its main theme")
+    description: str = Field(description="a clear and concise description of the PR using bullet points (with sub-bullets if needed). Prioritize the most significant changes first")
+    title: str = Field(description="a concise and descriptive title that captures the PR's main theme")
 =====