estimating-and-contingency

estimating-and-contingency is a skill for Claude Code from cbrock84/headcount. It costs 87 tokens per session (968 once invoked), scanned A, original, MIT.

A guide to producing cost or effort estimates that explain how the number was calculated and how uncertain it is. It covers breaking work into smaller parts, documenting assumptions, using ranges, and adding contingency separately from management reserve.

In plain words
What is it for?
Use it to build or review estimates for projects, compare estimation methods, document assumptions, and size contingency.
Why use it?
It reduces estimates that are padded, challenged, or treated as fixed promises despite uncertainty. It also helps expose missing work such as testing, data migration, training, and coordination.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the pmo plugin — 9 skills shipped together

Good fit Use it to build or review estimates for projects, compare estimation methods, document assumptions, and size contingency.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cbrock84/headcount/estimating-and-contingency
About the project

headcount is an organization of independently installable Claude Code plugins, each grouping skills for a department such as finance, security, or demand generation. Claude Code users install the departments they need and invoke their skills for specialized work; the catalogue entries are skills and related agent tooling from that organization.

cbrock84/headcount · 1,300 stars · on GitHub · cbrock84.github.io

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 cbrock84/headcount --skill estimating-and-contingency
Clone the repo
git clone --depth 1 https://github.com/cbrock84/headcount

Made for: Claude Code.

Or install pmo, the plugin that ships this one along with the rest of its 9 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 estimating-and-contingency

README.md
[![agentmods](https://agentmods.dev/badge/skills/cbrock84/headcount/estimating-and-contingency.svg)](https://agentmods.dev/skills/cbrock84/headcount/estimating-and-contingency)
Your own site
<a href="https://agentmods.dev/skills/cbrock84/headcount/estimating-and-contingency"><img src="https://agentmods.dev/badge/skills/cbrock84/headcount/estimating-and-contingency.svg" alt="Measured on agentmods" height="20"></a>
Per session 87 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 968 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00087 $0.00968
Opus 5 $0.00044 $0.00484
Sonnet 5 $0.00017 $0.00194
Haiku 4.5 $0.00009 $0.00097

Measured 3d ago against content hash 4dafe099046c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

estimating-and-contingency 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 3d ago.

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.

plugins/pmo/skills/estimating-and-contingency/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Estimating and contingency

An estimate is a claim about an uncertain future. Most organizations treat it as a commitment made by whoever said the number, which is why estimates are padded, disbelieved, and padded again.

Decompose before you estimate

Estimate the work, not the project. Break it down until each piece is small enough that someone who would do it can picture doing it — usually a week or two of effort. Below that you are estimating noise; above it you are guessing.

Two decomposition failures are worth naming. Missing scope is the larger one: integration, data migration, environments, testing, documentation, training, and the coordination overhead of everyone involved routinely go unestimated because nobody owns them. Double-counted contingency is the other: padding inside every task, then adding a reserve on top of the padded total.

Pick the method that matches what you know

  • Analogous — scale from a comparable past effort. Fast, needs real history, and the comparison has to survive being stated out loud: what is genuinely similar and what is not.
  • Parametric — a rate applied to a count. Cost per endpoint, per interface, per square foot, per test case. Credible only when the rate comes from your own data and the count is knowable.
  • Bottom-up — estimate each decomposed piece and roll up. Most accurate, most expensive, and worth it once the work is understood well enough for the pieces to be real.

Use two methods and compare them where the number matters. When they disagree by more than a quarter, one of them is built on an assumption nobody has stated.

Write the basis down, because that is the durable part

The number is the least useful output. The basis of estimate is what lets someone re-estimate later instead of starting over: what is included, what is explicitly excluded, the rates and quantities used, the assumptions the number depends on, and who provided each input.

An estimate without a basis cannot be defended, cannot be updated, and cannot be learned from. When the project comes in at double, the basis is what tells you whether the estimate was wrong or the work changed — and those call for opposite responses.

Read the full file on GitHub · 80 lines

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. 3d ago First seen · 80 lines · 87 tokens per session scan A 4dafe099046c

Subscribe to this mod's changes

estimating-and-contingency is a skill published in the GitHub repository cbrock84/headcount (1,300 stars, last pushed 4d ago), licensed MIT. It adds 87 tokens to every session and 968 once invoked, about $0.0004 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 2026-09-03.

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