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 commands/punt-labs/z-spec/b-check-devgit clone --depth 1 https://github.com/punt-labs/z-specWrote 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/commands/punt-labs/z-spec/b-check-dev)<a href="https://agentmods.dev/commands/punt-labs/z-spec/b-check-dev"><img src="https://agentmods.dev/badge/commands/punt-labs/z-spec/b-check-dev.svg" alt="Measured on agentmods" 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 | $0.00008 | $0.00604 |
| Opus 5 | $0.00004 | $0.00302 |
| Sonnet 5 | $0.00002 | $0.00121 |
| Haiku 4.5 | $0.00001 | $0.00060 |
Grade A, and why
b-check-dev 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 4d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- b-check — 95% identical, 2 lines differ
How it starts
The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Check B Machine with probcli
Type-check a B machine (.mch, .ref, or .imp) using probcli.
Input
File: $ARGUMENTS
Process
0. Check Prerequisites
Verify probcli is installed:
PROBCLI="${PROBCLI:-$HOME/Applications/ProB/probcli}"
if ! which probcli >/dev/null 2>&1 && [ ! -x "$PROBCLI" ]; then
echo "PROBCLI_NOT_FOUND"
fi
If probcli not found: Stop and tell the user:
probcli is not installed. Run
/z-spec-dev:setup-dev probclifirst.
1. Locate the Machine
If a file path is provided, use it directly.
If no file specified:
- Look in
specs/for.mch,.ref, or.impfiles - Present options if multiple files exist
2. Run probcli Type-Check
probcli <file>
probcli parses the machine, checks types, and reports errors. Unlike Z specifications (which use fuzz for type-checking), B machines use probcli for both type-checking and animation.
3. Interpret Results
Success: probcli exits with code 0, no error output.
Errors: probcli reports syntax errors, type errors, and well-formedness violations.
Common errors and fixes:
| Error | Likely Cause | Fix |
|---|---|---|
Syntax Error |
Invalid B syntax | Check clause order (SETS before VARIABLES before INVARIANT) |
Type Error |
Mismatched types in predicate | Verify variable types in INVARIANT match OPERATIONS usage |
Identifier not found |
Undefined variable or constant | Add to VARIABLES or CONSTANTS clause |
Parse error: expecting END |
Missing END keyword | Each PRE/IF/SELECT needs a matching END |
Not a B file |
Wrong file extension | Use .mch, .ref, or .imp |
PROPERTIES missing |
CONSTANTS without PROPERTIES | Add PROPERTIES clause with typing constraints |
4. Report Results
If successful:
- Confirm the machine type-checks
- List the machine's SETS, VARIABLES, and OPERATIONS
If errors:
- List each error with location
- Suggest specific fixes
- Offer to apply fixes
Reference
- B notation:
reference/b-notation.md - B machine patterns:
reference/b-machine-patterns.md - probcli options:
reference/probcli-guide.md
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.
- 4d ago First seen · 84 lines · 8 tokens per session scan A 52061f47425f
b-check-dev is a command published in the GitHub repository punt-labs/z-spec (5 stars, last pushed yesterday), licensed MIT. It adds 8 tokens to every session and 604 once invoked, about $0.0000 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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