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Equation 25 · Part 1 · The Token Tax of Giving a Model More Tools

Symbol tau_0

τ0\tau_0
τ0\tau_0

What this part means

tau0u_0 is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

tau0u_0 is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

Putting the pieces together gives a short, honest account of where a tool protocol’s overhead actually lives. A single request pays a fixed tool-use tax τ0\tau_0 the moment any tool is attached, plus roughly sˉ\bar{s} tokens for every one of the n tools visible in that request, repeated on every turn because the underlying inference API carries no memory between calls. Lazy discovery — Anthropic’s Tool Search Tool, or a disciplined use of MCP’s own…

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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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