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Equation 14 · Part 1 · The Economics, Energy, and Physical Limits of Tool Protocols and the Model Context Protocol

Symbol bart_tool

tˉtool\bar{t}_{\mathrm{tool}}
tˉtool\bar{t}_{\mathrm{tool}}

What this part means

the number of tokens.

Its job in the formula

barttt_tool 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

If every tool schema costs on average tˉtool\bar{t}_{\mathrm{tool}} tokens and all of them are injected in full on every turn, the maximum number of tools a deployment can nominally offer before it must start pruning or retrieving is

The passage around this formula

Put the three costs together and a deployment question comes into focus: given a fixed context window, how many tools can actually be offered before something has to give? A simple ceiling model makes the trade-off explicit. Let C be the model’s usable context window, TsystemT_{\mathrm{system}} the fixed cost of operator instructions, and TreserveT_{\mathrm{reserve}} a reserved allowance for the user’s message and the model’s own answer. If every tool schema costs on average tˉtool\bar{t}_{\mathrm{tool}} tokens and all of them are injected in full on every turn, the maximum number of tools a deployment can nominally offer before it must start pruning or retrieving is

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Sources cited in the article section

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