XML, Markdown, or JSON: Which gives LLMs the most reliable boundaries?

Name: XML, Markdown, or JSON: Which gives LLMs the most reliable boundaries?
Availability: InStock
Author: systima

by systima·Mar 5, 2026·3 points·2 comments

AI Analysis

●●SolidBig Brain

Settles the delimiter format debate with data—Markdown fails under adversarial inputs on MiniMax.

Strengths

•Rigorous methodology: 600 model calls, 600 human judge assessments, two rounds of increasing difficulty—cuts through anecdote-based advice.
•Actionable finding: 'format rarely matters' contradicts confident Anthropic/OpenAI recommendations, plus real exception (MiniMax+Markdown) moves beyond hand-waving.
•Open-sourced benchmark and raw data on GitHub enables reproducibility and follow-up research.

Weaknesses

•Audience is narrow: matters mainly to prompt engineers in regulated industries or adversarial threat models; 80% of teams won't change behavior.
•Tested only four frontier models (missing smaller open-source and reasoning models); MiniMax result feels like an outlier, not a trend.