HTML vs Markdown vs Plain Text for LLM Extraction

Choose the smallest representation that preserves the information your extraction task needs. Plain text can be sufficient for visible values. Markdown is a useful candidate when headings, tables and link destinations matter. Keep HTML when the answer depends on DOM attributes or script data that conversion removes.
We tested the same six-field extraction contract on three saved inputs, then on 15 hosted MCP returns. HTML produced correct records in each tested case. Markdown worked for the purchase-link case but returned empty arrays for the table. Local text worked for the table; hosted raw-mode text did not. These small, fixed-model results make the practical rule sharper: preserve the fields, then validate complete records before comparing cost.








