---
id: "concept-hard-wiring-vs-skills"
type: "concept"
source_timestamps: ["17:25:00", "17:30:00", "17:45:00"]
tags: ["architecture", "best-practices"]
related: ["claim-use-scripts-for-deterministic", "action-use-scripts-for-hardwiring", "contrarian-dont-use-skills-for-everything"]
definition: "The architectural distinction between using deterministic code (scripts) for hard-wired behavior and probabilistic plain-English instructions (skills) for reasoning."
sources: ["s43-file-format-agreement"]
sourceVaultSlug: "s43-file-format-agreement"
originDay: 43
---
# Hard Wiring: Scripts vs. Skills

## Definition

The architectural distinction between using **deterministic code (scripts)** for hard-wired behavior and **probabilistic plain-English instructions (skills)** for reasoning.

## The Boundary

A common mistake when transitioning to agentic workflows is trying to use LLM skills for everything. Nate B. Jones emphasizes a strict architectural boundary:

> *If you require hard-wired, deterministic behavior, you must use traditional code (scripts).*

Skills are written in plain English and are inherently probabilistic; they rely on the LLM's latent space to interpret and execute. While agents will generally respect and follow plain-English skills, they are **not guaranteed** to execute them with 100% fidelity every single time.

## When to Choose Which

| Use a **script** when... | Use a **skill** when... |
| --- | --- |
| The process must produce identical output every run | The task requires judgment or pattern matching |
| The cost of deviation is high (financial, legal, safety) | Edge cases require flexible reasoning |
| Logic is procedural and well-specified | Inputs are messy / require interpretation |
| You need exact APIs, math, or data integrity | The output is qualitative (analysis, drafting, summaries) |

## The Hybrid

Agents are powerful because they are general-purpose reasoning engines — they can and **should** invoke deterministic scripts as tools when absolute precision is required, reserving skills for tasks that need flexibility, pattern matching, and judgment. This is the *neuro-symbolic* hybrid pattern.

## Related

- [[claim-use-scripts-for-deterministic]]
- [[action-use-scripts-for-hardwiring]]
- [[contrarian-dont-use-skills-for-everything]]