Cutting tool output tokens in Microsoft Agent Framework with TOON

Tool call outputs in Microsoft Agent Framework (MAF) are normally JSON-serialized, which bloats context windows with repeated keys, braces and quotes for tabular data like order lists. TOON (Token-Oriented Object Notation) offers a line-oriented, YAML/CSV-like encoding that declares field names once for uniform arrays of objects, cutting 30-60% of tokens versus equivalent JSON per the TOON project's benchmarks. Since MAF tools just need to return a string, swapping a tool's return value to a TOON-serialized string (via the Toon.NET NuGet package) works without touching the JSON Schema MAF generates for tool parameters. The gain only matters for tabular, array-of-objects results like order histories or search results; single objects or non-uniform blobs see little benefit. Both MAF and current TOON encoders on NuGet are early/preview software, so pinning versions is advised before production use.

Source: https://bartwullems.blogspot.com/2026/09/cutting-tool-output-tokens-in-microsoft.html. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.