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 skills/mendixlabs/mxcli/check-syntaxnpx skills add mendixlabs/mxcli --skill check-syntaxgit clone --depth 1 https://github.com/mendixlabs/mxcliWhat 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 | $0.00056 | $0.04815 |
| Opus 5 | $0.00028 | $0.02407 |
| Sonnet 5 | $0.00011 | $0.00963 |
| Haiku 4.5 | $0.00006 | $0.00481 |
Grade A, and why
check-syntax 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.
How it starts
The opening of the file, as written. The whole thing — 448 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MDL Syntax Validation Skill
This skill ensures MDL scripts are validated before presenting them to users or executing them.
When to Use This Skill
ALWAYS use this skill before:
- Presenting MDL code to users
- Executing MDL scripts via
mxcli exec - Committing MDL files to version control
exec refuses what check rejects
mxcli exec runs the same semantic checks before writing anything. A script whose
checks report an error is not executed at all — nothing is written — because
exec applies statements one at a time and cannot roll back, so a known-bad
script would leave the model partly updated. Warnings are printed and do not stop
the run.
mxcli exec script.mdl -p app.mpr # checked, then applied
mxcli exec script.mdl -p app.mpr --no-check # applied regardless
This does not replace running check yourself. check is faster, needs no
write connection, and reports the warnings worth reading before you commit to a
run. What the gate guarantees is narrower and still valuable: a script that slips
past you cannot half-apply.
It also does not mean the script is correct. mxcli check validates MDL syntax
and mxcli's own rules; it does not validate the Mendix model. Run
mx check (or mxcli docker check -p app.mpr) after applying a slice.
-p resolves references — there is no separate opt-in
mxcli check script.mdl alone checks syntax and the semantic rules that need no
model. Pass -p and it also resolves every reference — modules, entities,
pages, microflows and icons — against that project:
mxcli check script.mdl # syntax + model-free rules
mxcli check script.mdl -p app.mpr # ... and every reference resolved
--references is implied by -p and is kept only so existing scripts keep
working. It used to be required, which meant mxcli check script.mdl -p app.mpr
printed an unqualified Check passed! having resolved nothing — a misspelled
icon or entity sailed through a command that had been handed the project. A run
without a project now says what it did not check, so a pass is never read as
more than it is.
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 · 448 lines · 56 tokens per session scan A 3e6819c76e81
check-syntax is a skill published in the GitHub repository mendixlabs/mxcli (115 stars, last pushed 2d ago), licensed Apache-2.0. It adds 56 tokens to every session and 4,815 once invoked, about $0.0003 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 2026-08-30.
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