[Bug]: Kimi K3 and MiniMax-M3 tool parsers raise on deeply nested or very long numeric JSON arguments #20993

System Info

• TensorRT-LLM main at 687359e (tensorrt_llm/serve/tool_parser/kimi_k3_tool_parser.py, tensorrt_llm/serve/tool_parser/minimax_m3_parser.py), pure Python. A CPU is enough to reproduce.
• Python 3.12
• Serving path: trtllm-serve ... --tool_parser kimi_k3 or --tool_parser minimax_m3, chat completions with tools

Who can help?

@NVIDIA/trt-llm-runtime-devs (CODEOWNERS for tensorrt_llm/serve)

Reproduction

from tensorrt_llm.serve.openai_protocol import ChatCompletionToolsParam
from tensorrt_llm.serve.tool_parser.kimi_k3_tool_parser import KimiK3ToolParser
from tensorrt_llm.serve.tool_parser.minimax_m3_parser import MiniMaxM3ToolParser

tools = [ChatCompletionToolsParam(function={
    "name": "f", "parameters": {"type": "object", "properties": {"v": {"type": "object"}}}})]
deep = "[" * 100000 + "]" * 100000

k3 = ('<|open|>tools<|sep|><|open|>call tool="f" index="1"<|sep|>'
      '<|open|>argument key="v" type="object"<|sep|>{}<|close|>argument<|sep|>'
      '<|close|>call<|sep|><|close|>tools<|sep|>')
KimiK3ToolParser().detect_and_parse(k3.format(deep), tools)        # RecursionError
KimiK3ToolParser().detect_and_parse(k3.format("9" * 4400), tools)  # ValueError (int digit limit)

m3 = (']<]minimax[>[<tool_call>\n]<]minimax[>[<invoke name="f">\n'
      ']<]minimax[>[<v>{}]<]minimax[>[</v>\n]<]minimax[>[</invoke>\n]<]minimax[>[</tool_call>')
MiniMaxM3ToolParser().detect_and_parse(m3.format(deep), tools)     # RecursionError

Expected behavior

An argument that json.loads cannot decode keeps its raw text, which is what both parsers already do for plain invalid JSON.

actual behavior

For kimi_k3 the error leaves both detect_and_parse and the streaming path (finish and the section close call detect_and_parse). For minimax_m3 it leaves detect_and_parse, which the non-streaming chat path calls directly, so the request fails with HTTP 400 and the generated text is lost. The minimax_m3 streaming path catches it and returns the raw text.

additional notes

KimiK3ToolParser._coerce_value and _parse_call_arguments catch only json.JSONDecodeError. A number with more than 4300 digits makes json.loads raise a plain ValueError (the CPython integer string limit), and deep nesting raises RecursionError. minimax_m3_parser._coerce_value catches ValueError and lets RecursionError through. A value just under the decoder's nesting limit decodes, and then the json.dumps of the arguments object, one level deeper, raises RecursionError. The 9997 depth is the boundary on CPython 3.12 and can differ on other versions. I have a fix with tests ready and will open a PR that references this issue.