cofounder-and-equity

cofounder-and-equity is a skill for Claude Code from impactbrussels/FounderOS. It costs 136 tokens per session (1,650 once invoked), scanned A, original, Apache-2.0.

A decision guide for choosing a co-founder and working out how to divide company ownership. It also covers questions about vesting, which means earning ownership over time.

In plain words
What is it for?
Use it to assess whether you need a co-founder, evaluate a potential partner, discuss difficult founder questions, and reason through an ownership split or what happens if someone leaves.
Why use it?
It helps founders avoid choosing a poor long-term partner or agreeing to an ownership split without discussing important risks. It also makes clear that legal, tax, and financial details need professional advice.

Skill for Claude Code

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

Part of the founderos plugin — 23 skills, 3 agents shipped together

Good fit Use it to assess whether you need a co-founder, evaluate a potential partner, discuss difficult founder questions, and reason through an ownership split or what happens if someone leaves.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/impactbrussels/founderos/cofounder-and-equity
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 impactbrussels/FounderOS --skill cofounder-and-equity
Clone the repo
git clone --depth 1 https://github.com/impactbrussels/FounderOS

Made for: Claude Code.

Or install founderos, the plugin that ships this one along with the rest of its 23 skills, 3 agents.

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 cofounder-and-equity

README.md
[![agentmods](https://agentmods.dev/badge/skills/impactbrussels/founderos/cofounder-and-equity/github.svg)](https://agentmods.dev/skills/impactbrussels/founderos/cofounder-and-equity)
Your own site
<a href="https://agentmods.dev/skills/impactbrussels/founderos/cofounder-and-equity"><img src="https://agentmods.dev/badge/skills/impactbrussels/founderos/cofounder-and-equity/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 cofounder-and-equity

Your own site · 80×15
<a href="https://agentmods.dev/skills/impactbrussels/founderos/cofounder-and-equity"><img src="https://agentmods.dev/badge/skills/impactbrussels/founderos/cofounder-and-equity.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 136 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,650 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 $0.00136 $0.01650
Opus 5 $0.00068 $0.00825
Sonnet 5 $0.00027 $0.00330
Haiku 4.5 $0.00014 $0.00165

Measured 9d ago against content hash 805b5300a529, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

cofounder-and-equity 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 9d 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.

skills/cofounder-and-equity/SKILL.md · 106 lines

How it starts

The opening of the file, as written. The whole thing — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Co-founder and Equity

Equity and legal specifics vary by jurisdiction and need a qualified lawyer. This skill helps you think clearly about whether to take a co-founder and how to reason about a split - it is not legal, tax, or financial advice. Vesting mechanics, share/option paperwork, and tax treatment differ by country and change over time. Have a lawyer paper the final agreement (see the legal-and-incorporation skill).

A co-founder is the highest-stakes relationship of your startup - more permanent than most marriages, with no easy exit and a four-way split of control, credit, and equity. Choosing the wrong one, or splitting equity on a hallway handshake, is one of the top reasons early startups implode. The cost is asymmetric: the right co-founder roughly doubles your odds; the wrong one, locked in with no vesting, can hold the company hostage. This skill helps you decide if you even need one, evaluate fit honestly, have the conversations everyone avoids, and split equity with reasoning you can both live with for a decade.

The method

Built on the Founder OS scaffold (High tier). Full question lists, frameworks, and scenarios in references/equity-split.md.

Step 1 - Decide if you even need a co-founder, and what gap they fill (ask before assuming)

A co-founder is not a default and not a hiring shortcut. Ask: what specific, critical gap can only be filled by a committed equal partner - not a hire, contractor, or advisor? Name the gap (skills, network, complementary domain, or the sheer stamina of two believers). If you can't name a real gap, you may want a first hire or an advisor, not a co-founder. The worst reason to take one is loneliness.

Step 2 - Evaluate fit before you commit (research before asserting)

Don't marry on the first date. Evaluate across four axes: values (do you agree on why you're building and what "winning" means?), skills (genuinely complementary, not overlapping?), commitment (full-time, financial runway, life stage, risk appetite?), and conflict style (how do they behave under stress and disagreement?). Gather evidence the only way that works: a period of "founder dating" plus a real trial project with a deadline and pressure. How someone handles a hard week together tells you more than any conversation.

Read the full file on GitHub · 106 lines

Files

What ships with it

1 file 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. 9d ago First seen · 106 lines · 136 tokens per session scan A 805b5300a529

Subscribe to this mod's changes

cofounder-and-equity is a skill published in the GitHub repository impactbrussels/FounderOS (2 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 136 tokens to every session and 1,650 once invoked, about $0.0007 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.