Equation 3 · Part 6 · Function Calling, MCP, and the Other Ways to Give a Model Tools
subscript
subscript
What this part means
The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.
Its job in the formula
A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.
Full expression→subscript→Article meaning
The passage around this formula
That combinatorial framing is worth making explicit, as a stylized model rather than a measured cost curve. Call the number of distinct model-facing client applications M and the number of distinct external tools or data sources N . Absent any shared protocol, a connector is needed for each pairing that is actually wanted, so the number of bespoke integrations that must be built and separately kept current scales as . A protocol that both sides target once, instead, lets each side write a single adapter to the shared standard, so the count becomes
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.
Open the illustrated subscripts: which member of a family? guide →
Sources cited in the article section
- [5] Introducing the Model Context Protocol ↗
- [6] Specification ↗
- [7] Server Features: Tools ↗
- [8] Authorization ↗
- [4] Tool use with Claude ↗
These citations provide research context; check each source for the exact claim it supports.