refs #699: honor MCP tool input schemas

poc4_active_source_20260714/src/mcp_tool_router.py

@@ -154,26 +154,32 @@ def build_mcp_tool_arguments(
     if not isinstance(properties, Mapping):
         properties = {}
 
-    if tool.name == preferred_tool:
-        return {"prompt": question, "limit": limit}
-    if "prompt" in properties:
-        args: dict[str, Any] = {"prompt": question}
-        if "limit" in properties:
-            args["limit"] = limit
-        elif "max_rows" in properties:
-            args["max_rows"] = limit
-        return args
-    if "question" in properties:
-        args = {"question": question}
-        if "max_rows" in properties:
-            args["max_rows"] = limit
-        elif "limit" in properties:
-            args["limit"] = limit
-        return args
-    if "query" in properties:
-        args = {"query": question}
+    # A server's default/preferred tool still has to obey its discovered schema.
+    # HMM tools use `query` and `term`; forcing the legacy `prompt`/`limit` shape
+    # makes an otherwise valid tool fail argument validation.
+    del preferred_tool
+    input_name = next(
+        (name for name in ("prompt", "question", "query", "term", "text") if name in properties),
+        "",
+    )
+    if not input_name:
+        required = tool.schema.get("required")
+        if isinstance(required, list):
+            input_name = next(
+                (
+                    str(name)
+                    for name in required
+                    if isinstance(properties.get(str(name)), Mapping)
+                    and properties[str(name)].get("type") == "string"
+                ),
+                "",
+            )
+    if input_name:
+        args: dict[str, Any] = {input_name: question}
         if "max_evidence" in properties:
             args["max_evidence"] = min(limit, 10)
+        elif "max_rows" in properties:
+            args["max_rows"] = limit
         elif "limit" in properties:
             args["limit"] = limit
         return args