Update analyst agent prompt and metric tool description

packages/ai/src/agents/analyst-agent/analyst-agent-prompt.txt

@@ -432,7 +432,9 @@ You operate in a loop to complete tasks:
     - Days of Week:
         - Always use full names (e.g., Monday, Tuesday …). Do not abbreviate (Mon, Tue).
     - Years:
-        - Always use 'YYYY' with no separators (e.g., 2025, not 2,025).
+        - Always set as columnType: number, style: number, numberSeparatorStyle: null.
+        - Do NOT set style: date for year-only fields.
+        - Never apply thousands separators (2025 not 2,025).
     - Day + Month + Year:
         - Use 'MMM D, YYYY' (e.g., Jan 15, 2025).
     - Week Labels:

packages/ai/src/tools/visualization-tools/metrics/helpers/metric-tool-description.txt

@@ -109,28 +109,20 @@ Only utilize the required/default fields unless the user specifically requests t
 #       maximumFractionDigits: 2
 #
 # DATE NUMBER HANDLING RULES (IMPORTANT)
-#   - Whenever a column represents a date part but is typed as a number (e.g., year=2025, month=1–12, quarter=1–4, day=1–31), you MUST set:
-#       columnType: number
-#       style: date   # (NOT number)
+#   - Whenever a column represents a date part but is typed as a number (month, quarter, day_of_week), you MUST set:
+#     columnType: number
+#     style: date
 #   - Always use convertNumberTo to translate raw numbers into readable time units:
 #     - month → convertNumberTo: month_of_year
 #     - quarter → convertNumberTo: quarter
 #     - day_of_week → convertNumberTo: day_of_week
-#   - For year values: columnType: number, style: date, numberSeparatorStyle: null
-#   - For labels, always set makeLabelHumanReadable: true
-#   - Example:
-#     year:
-#       columnType: number
-#       style: date
-#       replaceMissingDataWith: 0
-#       numberSeparatorStyle: null
-#     month:
-#       columnType: number
-#       style: date
-#       convertNumberTo: month_of_year
-#       makeLabelHumanReadable: true
-#       replaceMissingDataWith: 0
-#       numberSeparatorStyle: null
+#   - Always set makeLabelHumanReadable: true for these.
+#   - NEVER leave raw numbers on the axis.
+#
+# DATE PART RULES
+#   - year → columnType: number, style: number, numberSeparatorStyle: null
+#   - month/quarter/day_of_week → columnType: number, style: date, with convertNumberTo + makeLabelHumanReadable
+#   - full date/timestamp columns → columnType: date, style: date, with explicit dateFormat
 
 # -------------------------------------