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Equation 2 · Part 1 · From Origins to Frontier: A History of Claude Code and Agentic Development Tools

Symbol T_50

T50(t)T_{50}(t)
T50T_{50}

What this part means

the length of task, measured in human-hours, that a frontier agent could complete autonomously with 50% reliability at time t.

Its job in the formula

T5T_50 is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Where the article explains it

where T50(t)T_{50}(t) is the length of task, measured in human-hours, that a frontier agent could complete autonomously with 50% reliability at time t .

The passage around this formula

where T50(t)T_{50}(t) is the length of task, measured in human-hours, that a frontier agent could complete autonomously with 50% reliability at time t . This is an empirical regression over six years of a specific evaluation methodology, not a law of nature, and METR’s own reporting is explicit that the trend could bend in either direction; it is included here because it is the clearest available answer to “how would you know if agentic coding tools were actually getting more autonomous,” as distinct from “how would you know if a vendor said so.”

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the article section

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