[feat] Add SGLANG_TOOL_STRICT_LEVEL for tool-call behavior control (#12423)

Signed-off-by: Xinyuan Tong <xinyuantong.cs@gmail.com>

python/sglang/srt/function_call/function_call_parser.py

@@ -8,6 +8,7 @@ from sglang.srt.entrypoints.openai.protocol import (
     ToolCallConstraint,
     ToolChoice,
 )
+from sglang.srt.environ import ToolStrictLevel, envs
 from sglang.srt.function_call.base_format_detector import BaseFormatDetector
 from sglang.srt.function_call.core_types import ToolCallItem
 from sglang.srt.function_call.deepseekv3_detector import DeepSeekV3Detector
@@ -62,6 +63,7 @@ class FunctionCallParser:
 
         self.detector = detector
         self.tools = tools
+        self.tool_strict_level = envs.SGLANG_TOOL_STRICT_LEVEL.get()
 
     def has_tool_call(self, text: str) -> bool:
         """
@@ -142,7 +144,10 @@ class FunctionCallParser:
             info = get_structure_info(name)
 
             # accept all if not strict, otherwise only accept the schema
-            schema = function.parameters if function.strict else {}
+            is_strict = (
+                function.strict or self.tool_strict_level >= ToolStrictLevel.PARAMETER
+            )
+            schema = function.parameters if is_strict else {}
 
             tool_structures.append(
                 StructuresResponseFormat(
@@ -180,7 +185,10 @@ class FunctionCallParser:
         if (
             self.detector.supports_structural_tag()
             and tool_choice == "auto"
-            and any(tool.function.strict for tool in self.tools)
+            and (
+                any(tool.function.strict for tool in self.tools)
+                or self.tool_strict_level >= ToolStrictLevel.FUNCTION
+            )
         ):
             tag = self.get_structure_tag()
             return ("structural_tag", tag)