agent-design

agent-design is a skill for Claude Code from krzysztofsurdy/code-virtuoso. It costs 51 tokens per session (3,161 once invoked), scanned A, original, MIT.

A framework-independent guide to designing language-model agents and workflows. It explains when to use a fixed sequence of code versus a model-controlled loop, and how to set limits, permissions, memory, and recovery.

In plain words
What is it for?
Use it before choosing a framework or reviewing an agent design, especially for stop conditions, tool access, context selection, approval, memory, and multi-agent decisions.
Why use it?
It helps avoid adding unnecessary agent loops or multiple agents, which increase cost and coordination. It also focuses on the controls that make an agent safe and reliable when it runs without constant supervision.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions subagents; mentions Claude Code.

Part of the ai-virtuoso plugin — 4 skills shipped together

Good fit Use it before choosing a framework or reviewing an agent design, especially for stop conditions, tool access, context selection, approval, memory, and multi-agent decisions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/krzysztofsurdy/code-virtuoso/agent-design
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add krzysztofsurdy/code-virtuoso --skill agent-design
Clone the repo
git clone --depth 1 https://github.com/krzysztofsurdy/code-virtuoso

Made for: Claude Code.

Or install ai-virtuoso, the plugin that ships this one along with the rest of its 4 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for agent-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/krzysztofsurdy/code-virtuoso/agent-design/github.svg)](https://agentmods.dev/skills/krzysztofsurdy/code-virtuoso/agent-design)
Your own site
<a href="https://agentmods.dev/skills/krzysztofsurdy/code-virtuoso/agent-design"><img src="https://agentmods.dev/badge/skills/krzysztofsurdy/code-virtuoso/agent-design/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for agent-design

Your own site · 80×15
<a href="https://agentmods.dev/skills/krzysztofsurdy/code-virtuoso/agent-design"><img src="https://agentmods.dev/badge/skills/krzysztofsurdy/code-virtuoso/agent-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,161 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00051 $0.03161
Opus 5.5 $0.00020 $0.01264
Sonnet 5.5 $0.00010 $0.00632
Haiku 4.5 $0.00005 $0.00316

Measured yesterday against content hash c4e10c163e62, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

agent-design scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/ai/agent-design/SKILL.md · 159 lines

How it starts

The opening of the file, as written. The whole thing — 159 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent design

An LLM agent is a loop: the model picks a tool, the harness runs it, the result goes back into context, and the loop repeats until a stop condition fires. Most of the quality, cost, and safety of the system comes from the harness around that loop, not from the prompt. This skill holds the design decisions that hold across frameworks and model vendors. Library syntax changes monthly, so fetch it through docs-lookup instead of recalling it.

Core principles

Principle Meaning
Simplest thing that works A single model call with good context beats a loop. A loop beats multi-agent. Add structure only when a measured failure demands it
Workflow before agent If you can draw the steps before the run, write them as code. Let the model choose steps only when the path cannot be predicted
The harness is the product Stop conditions, caps, permissions, and recovery decide whether the agent is safe to run unattended
Context is a budget Reliability falls as context grows. Curate what the model sees at each step
Output is untrusted input Tool arguments, structured output, and retrieved text can be wrong or hostile. Validate and authorize in code
Evals before architecture changes Without a task set, you cannot tell whether a pattern, model, or framework helped

Workflow or agent

Anthropic's definitions: a workflow runs LLMs and tools through predefined code paths, and an agent lets the LLM direct its own process and tool use (Building effective agents).

Question Workflow Agent
Can you list the steps in advance? Yes No, the number of steps depends on what the tools return
Cost and latency Predictable, lower Variable, higher, with compounding-error risk
Testing Test each step, then the chain Test trajectories and outcomes, many trials per task
Failure mode A step fails in a known place The model wanders, loops, or stops early
Typical fit Extraction, classification, report generation, support triage Coding, open-ended research, multi-system operations

Read the full file on GitHub · 159 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 159 lines · 51 tokens per session scan A c4e10c163e62

Subscribe to this mod's changes

agent-design is a skill published in the GitHub repository krzysztofsurdy/code-virtuoso (36 stars, last pushed today), licensed MIT. It adds 51 tokens to every session and 3,161 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-22.

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