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 agentmods add rules/markmhendrickson/foundation/plan_sections_rulesgit clone --depth 1 https://github.com/markmhendrickson/foundationWhat 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 | $0.00355 | $0.00355 |
| Opus 5 | $0.00178 | $0.00178 |
| Sonnet 5 | $0.00071 | $0.00071 |
| Haiku 4.5 | $0.00036 | $0.00036 |
Grade A, and why
plan_sections_rules 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.
What it actually says
Plan Sections
When creating or updating a plan, structure it around the decision the user needs to make and the work that will follow.
Requirements
- Include a
Goalssection when the plan would benefit from a clear statement of desired outcomes. - Include a
Problemssection when the plan is addressing pain points, failure modes, blockers, or current-state gaps. - Include a
Solutionssection when the plan proposes concrete approaches, design responses, or implementation choices. - Include an
Automated testssection when testing is relevant to the work, especially for code changes, integrations, workflows, or regressions. - Omit any of these sections only when they would be empty, redundant, or not useful for the specific plan.
Guidance
- Keep the sections concise and proportional to the scope of the plan.
- Use explicit section headings so the structure is easy to scan.
- For small plans, each section can be brief; the requirement is about coverage, not verbosity.
- Do not force the
Automated testssection for plans where no meaningful automated verification exists, but address testing whenever it materially reduces risk.
Examples
Good
- A feature or architecture plan with
Goals,Problems,Solutions, andAutomated tests. - A lightweight operational plan with
GoalsandSolutions, while omittingAutomated testsif no testable system change is involved.
Bad
- A plan that jumps straight into tasks without clarifying the problem being solved.
- A code-change plan that omits testing considerations even though regressions are plausible.
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.
- yesterday First seen · 36 lines · 355 tokens per session scan A c40b95943eff
plan_sections_rules is a cursor rule published in the GitHub repository markmhendrickson/foundation (2 stars, last pushed 1mo ago), licensed MIT. It adds 355 tokens to every session, about $0.0018 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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