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Fix: Handle $ref in json-schema in qwen3_coder tool parser #37652

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Fix: Handle $ref in json-schema in qwen3_coder tool parser #37652

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84f5e48
Handle json-refs as objects
schoennenbeck Mar 20, 2026
844f151
Avoid ast parsing on refs
schoennenbeck Mar 20, 2026
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28 changes: 25 additions & 3 deletions vllm/tool_parsers/qwen3coder_tool_parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -157,12 +157,16 @@ def _convert_param_value(
and "type" in param_config[param_name]
):
param_type = str(param_config[param_name]["type"]).strip().lower()
elif (
isinstance(param_config[param_name], dict)
and "anyOf" in param_config[param_name]
elif isinstance(param_config[param_name], dict) and (
"anyOf" in param_config[param_name]
):
# anyOf has no top-level "type"; treat as object to trigger json.loads.
param_type = "object"
Comment on lines +160 to 164
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@gemini-code-assist gemini-code-assist bot Mar 20, 2026

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high

This change correctly identifies parameters defined with $ref, but making the broad assumption that they are always of object type could lead to incorrect behavior.

A $ref can point to a definition of any type, including primitives like string or integer. If a $ref points to a string type, but the model returns a value that looks like a dictionary (e.g., "{'key': 'value'}"), the current logic would incorrectly parse it as a dictionary via ast.literal_eval in the fallback path, instead of treating it as a string. This would result in a type mismatch and potential runtime errors in the tool-using code.

A safer approach would be to handle $ref parameters separately, perhaps by attempting to parse them with json.loads and falling back to treating them as a raw string if parsing fails, without attempting ast.literal_eval. This would correctly handle object-like values while not misinterpreting string literals that happen to look like Python literals.

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@schoennenbeck schoennenbeck Mar 20, 2026

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Switched to more restrictive parsing, avoiding the ast.literal_eval for refs.

elif isinstance(param_config[param_name], dict) and (
"$ref" in param_config[param_name]
):
# $ref has no type information at this level; treat it separately.
param_type = "$ref"
else:
param_type = "string"
if param_type in ["string", "str", "text", "varchar", "char", "enum"]:
Expand Down Expand Up @@ -214,6 +218,24 @@ def _convert_param_value(
func_name,
)
return param_value == "true"
elif param_type == "$ref":
# For $ref types, we don't have direct type information here.
# Attempt JSON parsing first, then fallback to string.
# We avoid ast.literal_eval for $ref types due to potential complexity and
# security concerns.
try:
param_value = json.loads(param_value)
return param_value
except (json.JSONDecodeError, TypeError, ValueError):
logger.debug(
"Parsed value '%s' of parameter '%s' cannot be "
"parsed with json.loads for $ref type in tool '%s', "
"degenerating to string.",
param_value,
param_name,
func_name,
)
return param_value
else:
if (
param_type in ["object", "array", "arr"]
Expand Down
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