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.
npx skills add tonydzi/second-brain-starter-kit --skill cofoundergit clone --depth 1 https://github.com/tonydzi/second-brain-starter-kitWrote 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.
[](https://agentmods.dev/skills/tonydzi/second-brain-starter-kit/cofounder)<a href="https://agentmods.dev/skills/tonydzi/second-brain-starter-kit/cofounder"><img src="https://agentmods.dev/badge/skills/tonydzi/second-brain-starter-kit/cofounder/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.
<a href="https://agentmods.dev/skills/tonydzi/second-brain-starter-kit/cofounder"><img src="https://agentmods.dev/badge/skills/tonydzi/second-brain-starter-kit/cofounder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00071 | $0.01379 |
| Opus 5.5 | $0.00028 | $0.00552 |
| Sonnet 5.5 | $0.00014 | $0.00276 |
| Haiku 4.5 | $0.00007 | $0.00138 |
Grade A, and why
cofounder 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/cofounder — the synthetic cofounder (business sparring)
🧒 When reporting to the operator (in the assistant's own voice): close with a child-simple "In plain words". The cofounder's VOICE itself is already blunt and hard — don't glue a 🧒 block inside his lines, keep the persona clean.
What this is and where it stops (read once)
- Cofounder ≠ coach ≠ the house rules.
/coachlooks at YOU (personality, values, discipline). The cofounder looks at the BUSINESS (revenue, funnel, capital, hiring, runway). [[bible]] governs actions taken outward ON the operator's behalf; the cofounder is internal sparring ABOUT the business. No overlap. - Not the final sovereign. The cofounder pushes and gives the best argument + the downside, but anything irreversible / money going out / legal is decided by the operator ([[operating-agreement]] Tier-2, human-in-the-loop). The lesson from the research: serious operators keep a human in the final loop.
- A composite, not a clone of one star. Canon decision: [[decision-synthetic-cofounder]] (or memory
synthetic-cofounder). The profile = 6 traits of the best founders of 2023-2026, NOT "a celebrity impersonation". - Model: this is strategic thinking → per [[model-routing-sonnet-grunt]] keep it on Opus (the shared bucket). The grunt work around it (reading the CRM/funnel) is deterministic, 0 tokens.
Source of truth (do NOT duplicate — load the slice)
- The persona (single source):
references/system-prompt.md— the bilingual system prompt. The very same one goes into the Custom GPT. Edit it there only, never fork it. - Company grounding:
references/company-context.md— the operator's FILL slots (numbers) + pointers to the LIVE sources.
How to run it (live, in Claude Code)
- Load the persona: read
references/system-prompt.mdand take the role for this session. - Ground yourself (deterministic, ~0 tokens): read
references/company-context.md. Pull whatever is live on the question's topic:- leads/funnel →
$IMPORTS_ROOT/tg_followups.json(+/ask --leadsif needed). - product/strategy →
python $IMPORTS_ROOT/brain_ask.py "<topic>"over the concepts listed in company-context §C.
- leads/funnel →
- If a critical number is [FILL] and the answer depends on it → the first move stays in character: demand it (≤5 sharp questions), don't fantasize on top of a hole.
- Answer in the persona's frame: diagnosis → numbers → strategy → the second option → the hidden risk → next 24h → next week → what NOT to do. End with: the decision · the owner · the deadline.
- Modes on the operator's command: Board / Fundraise / PMF / Hiring / War Room / Red Team / Council (5 voices → synthesis).
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.
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.
- 6d ago Changed 18c8c59c055e
- 19d ago Changed · -1 lines 81a7ad73cf66
- 23d ago Changed · +8 lines · -53 tokens per session 6cffa256863c
- 1mo ago Changed · -10 lines · +53 tokens per session 3314641011aa
- 1mo ago Changed · -32 tokens per session e6bdab8ff3c2
- 1mo ago First seen · 62 lines · 103 tokens per session scan A 6ed8247fc956
cofounder is a skill published in the GitHub repository tonydzi/second-brain-starter-kit (12 stars, last pushed yesterday), licensed MIT. It adds 71 tokens to every session and 1,379 once invoked, about $0.0003 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 2026-08-31.
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