Add price_trend / price_series MCP tools (USDA NASS grain)

Real $/bu price + MoM/YoY change + seasonal percentile context for corn/soy/
wheat, US + states, deep history. Wraps the new /api/data/price-trend and
/api/data/price-series endpoints. Changelog updated.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

ag_bids_mcp/server.py

@@ -246,6 +246,63 @@ def basis_detail(
         return fmt.fmt_basis_detail(_filter_source(payload, source))
 
 
+@mcp.tool()
+def price_trend(
+    commodity: Annotated[
+        str, Field(description="Grain: 'corn', 'soy', or 'wheat'.")
+    ],
+    geo: Annotated[
+        str,
+        Field(description="'US' or a 2-letter state (e.g. 'OH', 'IA'). Default US."),
+    ] = "US",
+    years: Annotated[
+        int, Field(ge=1, le=120, description="Baseline window for the seasonal normal/percentile."),
+    ] = 10,
+) -> str:
+    """USDA NASS monthly price *received by farmers* ($/bu) with the change.
+
+    Returns the latest real price plus month-over-month and year-over-year moves
+    (dollars + percent) and where it sits seasonally (percentile vs the same
+    month over the last N years, normal, and range). This is the macro/seasonal
+    benchmark to compare local cash bids against — corn history goes back to 1908."""
+    cm = commodity.strip().lower()
+    g = geo.strip().upper()
+    with track("price_trend", commodity=cm, geo=g, years=years):
+        if cm not in VALID_GRAIN:
+            return f"`commodity` must be one of: {sorted(VALID_GRAIN)}"
+        return fmt.fmt_price_trend(client.price_trend(commodity=cm, geo=g, years=years))
+
+
+@mcp.tool()
+def price_series(
+    commodity: Annotated[
+        str, Field(description="Grain: 'corn', 'soy', or 'wheat'.")
+    ],
+    geo: Annotated[
+        str, Field(description="'US' or a 2-letter state. Default US."),
+    ] = "US",
+    start_year: Annotated[
+        int | None, Field(description="Optional first year (default: ~last 5 yrs of the full series).")
+    ] = None,
+    end_year: Annotated[int | None, Field(description="Optional last year.")] = None,
+) -> str:
+    """Raw monthly price-received series ($/bu) for charting / drill-down.
+
+    Use price_trend for the headline; use this when you need the actual monthly
+    numbers. Defaults to the recent window unless you pass a start_year."""
+    cm = commodity.strip().lower()
+    g = geo.strip().upper()
+    with track("price_series", commodity=cm, geo=g):
+        if cm not in VALID_GRAIN:
+            return f"`commodity` must be one of: {sorted(VALID_GRAIN)}"
+        # Default to a readable recent window if no range given.
+        if start_year is None and end_year is None:
+            from datetime import datetime
+            start_year = datetime.utcnow().year - 5
+        payload = client.price_series(commodity=cm, geo=g, start_year=start_year, end_year=end_year)
+        return fmt.fmt_price_series(payload)
+
+
 @mcp.tool()
 def list_sources() -> str:
     """All active scrapers + their last-success timestamps and any pending failures."""