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.
git clone --depth 1 https://github.com/markmhendrickson/foundationWrote 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/rules/markmhendrickson/foundation/agent_constraints)<a href="https://agentmods.dev/rules/markmhendrickson/foundation/agent_constraints"><img src="https://agentmods.dev/badge/rules/markmhendrickson/foundation/agent_constraints/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/rules/markmhendrickson/foundation/agent_constraints"><img src="https://agentmods.dev/badge/rules/markmhendrickson/foundation/agent_constraints.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 | $0.00027 | $0.01950 |
| Opus 5.5 | $0.00011 | $0.00780 |
| Sonnet 5.5 | $0.00005 | $0.00390 |
| Haiku 4.5 | $0.00003 | $0.00195 |
Grade A, and why
agent_constraints 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 1mo 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 — 198 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent Constraints Rule
Reference: foundation/conventions/documentation_standards.md - Documentation standards
Purpose
Ensures agents enforce all absolute constraints, forbidden patterns, and validation requirements when working on the repository.
Scope
This document defines:
- Absolute constraints that agents MUST enforce
- Project positioning constraints (if configured)
- Constraints agents must enforce
- Communication constraints
- Forbidden patterns
- Validation checklist
This document does NOT cover:
- Repository-specific constraints (configured in
foundation-config.yaml) - Risk management and hold points (see
risk_management.md)
Configuration
Configure project-specific constraints in foundation-config.yaml:
agent_instructions:
enabled: true
constraints: [] # Repository-specific constraints
# Example:
# - "Never violate architectural boundaries"
# - "Always follow schema-first principles"
# - "Enforce immutability for core data"
validation_checklist:
enabled: true
custom_checks: [] # Repository-specific validation checks
Constraints are configurable per repository. Default constraints shown below can be customized or extended in foundation-config.yaml.
Absolute Constraints
Agents MUST enforce these constraints at all times (customize in foundation-config.yaml):
- Never violate architectural boundaries (respect layer boundaries, no cross-layer violations)
- Never introduce nondeterminism (no random IDs, no unstable logic, deterministic outputs)
- Never generate features outside project scope (stay within defined boundaries)
- Always follow project principles (schema-first, type-driven, or project-specific patterns)
- Enforce data integrity (immutability where required, proper validation)
- Enforce safety and explicit control (user approval where required, no implicit actions)
- Always output validated artifacts (code, specs, docs must pass validation)
- Follow project positioning (when creating marketing/content, follow project differentiators if configured)
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.
- 1mo ago First seen · 198 lines · 27 tokens per session scan A 806f340e8c32
agent_constraints is a cursor rule published in the GitHub repository markmhendrickson/foundation (2 stars, last pushed 2mo ago), licensed MIT. It adds 27 tokens to every session and 1,950 once invoked, about $0.0001 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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