brendan

brendan is a skill for Claude Code, Codex from drubinstein/terry. It costs 163 tokens per session (3,583 once invoked), scanned A, original, MIT.

A troubleshooting skill based on the USE method: for every system resource, check utilisation, saturation and errors. Saturation means work is waiting because a resource cannot handle it immediately.

In plain words
What is it for?
Use it to investigate performance regressions, saturation and capacity problems across resources such as processors, memory, storage and networks.
Why use it?
It replaces guessing about a slow or overloaded system with a repeatable way to identify the actual bottleneck.

Skill for Claude CodeCodex

Part of the terry plugin — 6 skills shipped together

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.

agentmods
npx agentmods add skills/drubinstein/terry/brendan
Any agent
npx skills add drubinstein/terry --skill brendan
Clone the repo
git clone --depth 1 https://github.com/drubinstein/terry

Made for: Claude Code, Codex.

Or install terry, the plugin that ships this one along with the rest of its 6 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 brendan

README.md
[![agentmods](https://agentmods.dev/badge/skills/drubinstein/terry/brendan.svg)](https://agentmods.dev/skills/drubinstein/terry/brendan)
Your own site
<a href="https://agentmods.dev/skills/drubinstein/terry/brendan"><img src="https://agentmods.dev/badge/skills/drubinstein/terry/brendan.svg" alt="Measured on agentmods" height="20"></a>
Per session 163 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,583 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00163 $0.03583
Opus 5 $0.00081 $0.01792
Sonnet 5 $0.00033 $0.00717
Haiku 4.5 $0.00016 $0.00358

Measured 4d ago against content hash 974466d8a970, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

brendan 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 4d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (templates/60s-triage.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/brendan/SKILL.md · 241 lines

How it starts

The opening of the file, as written. The whole thing — 241 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Brendan — systems-performance methodology (the USE method & friends)

Brendan is the measure-don't-guess discipline you run when a system is slow, saturated, or near capacity. It is Brendan Gregg's body of performance methodology — most of all the USE method — distilled into a skill: instead of reaching for whatever tool you remember (the streetlight anti-method) or blaming the component you touched last, you walk a complete list of resources and, for each, check three things — Utilization, Saturation, Errors — until the bottleneck names itself.

USE in one line: For every resource, check utilization, saturation, and errors. It finds ~80% of server issues with ~5% of the effort.

It is the generalization of three metric types applied to every resource:

  • Utilization — the average time the resource was busy servicing work, as a percent over an interval. (Caveat: a 5-min average of 20% can hide 100% bursts.)
  • Saturation — the degree of extra work the resource can't service, usually queued. Any non-zero saturation is a problem.
  • Errors — the count of error events. Check these first: they're quick to read and easy to interpret.

…and the spine that makes it a method: a complete resource list you refuse to leave gaps in — CPUs, memory capacity, network interfaces, storage device I/O, storage capacity, storage/network controllers, and the CPU/memory/I/O interconnects — each crossed off only when U, S, and E are all accounted for.

When to use

Use Brendan whenever you face a resource-bottleneck or capacity question and want a systematic sweep instead of a hunch. Typical shapes:

  • "the box/app/cluster is slow" with no obvious cause — run the sweep
  • a latency or throughput regression you need to localize to a resource
  • capacity planning / "are we near a limit?" / headroom questions
  • a saturation symptom (rising queues, tail latency, page-ins, packet drops)
  • GPU under-utilization or stalls in an ML/HPC job — note nvidia-smi "GPU-Util" = any kernel running, not SM occupancy, so 100% can still be starved; check true SM activity (dmon sm% / DCGM SM_ACTIVE)
  • the first 60 seconds on an unfamiliar Linux host (the triage checklist)
  • before you reach for perf/flamegraphs — USE first tells you which resource is worth profiling

Read the full file on GitHub · 241 lines

Files

What ships with it

6 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. 4d ago First seen · 241 lines · 163 tokens per session scan A 974466d8a970

Subscribe to this mod's changes

brendan is a skill published in the GitHub repository drubinstein/terry (1 stars, last pushed 2mo ago), licensed MIT. It adds 163 tokens to every session and 3,583 once invoked, about $0.0008 per session on Opus 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 2026-08-31.

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