Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/mendixlabs/mxclinpx agentmods add skills/mendixlabs/mxcli/check-syntaxWrote 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/mendixlabs/mxcli/check-syntax)<a href="https://agentmods.dev/skills/mendixlabs/mxcli/check-syntax"><img src="https://agentmods.dev/badge/skills/mendixlabs/mxcli/check-syntax/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/mendixlabs/mxcli/check-syntax"><img src="https://agentmods.dev/badge/skills/mendixlabs/mxcli/check-syntax.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 5 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Tool Misuse · line 27 Tool parameters are crafted to achieve unintended or unsafe behavior. Parameter abuse can bypass intended safety checks (e.g. shell=True, --force, dangerous glob patterns).Fix: Validate all tool parameters against an allowlist. Reject dangerous parameter values (shell=True, --force, -rf /) and use safe defaults.
- high Agent Snooping · line 306 Skill reads from agent configuration directories (.claude/, .codex/, .gemini/). These directories may contain API keys, personal settings, and other credentials that the skill has no legitimate need to access.Fix: Remove all code or instructions that access agent configuration directories (.claude/, .codex/, .gemini/). If configuration values are needed, pass them explicitly as parameters or environment variabl
- high Agent Snooping · line 307 Skill reads from agent configuration directories (.claude/, .codex/, .gemini/). These directories may contain API keys, personal settings, and other credentials that the skill has no legitimate need to access.Fix: Remove all code or instructions that access agent configuration directories (.claude/, .codex/, .gemini/). If configuration values are needed, pass them explicitly as parameters or environment variabl
- medium Agent Snooping · line 306 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
- medium Agent Snooping · line 307 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 | $0.00056 | $0.08607 |
| Opus 5.5 | $0.00022 | $0.03443 |
| Sonnet 5.5 | $0.00011 | $0.01721 |
| Haiku 4.5 | $0.00006 | $0.00861 |
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 today.
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 — 706 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Find it fast
sed -n '<from>,<to>p' SKILL.md one section rather than reading the file;
./mxcli syntax <topic> answers how do I write this for a fraction of either.
| lines | section |
|---|---|
| 29-35 | When to Use This Skill |
| 36-286 | exec refuses what check rejects |
| 287-422 | Pre-Flight Validation Checklist |
| 423-458 | Two rules that only real validation used to catch |
| 459-505 | Validation Workflow |
| 506-527 | Script Execution Behavior |
| 528-588 | Script Organization |
| 589-641 | Troubleshooting Parse Errors |
| 642-699 | Studio Pro MCP — Verification Only |
| 700-705 | Related Skills |
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. Warnings
are printed and do not stop the run. A statement that still fails while it is
written is rolled back with the rest (see Script Execution Behavior).
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.
What ships with it
2 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.
- today Changed · -15 lines c87853bc108f
- yesterday Changed 812000bf77be
- 2d ago Changed dee7b0d108df
- 5d ago Changed · +20 lines 5ea666aa1a68
- 6d ago Changed 1de1acb1a26f
- 13d ago Changed · +24 lines 47e7ded74211
- 13d ago Changed · +21 lines bbe7fbe6c4d5
- 14d ago Changed · +29 lines 88c15577dc93
- 15d ago Changed · +2 lines 6ef4c9ff6d8b
- 20d ago First seen · 625 lines · 56 tokens per session scan A f2e5aec9fef7
check-syntax is a skill published in the GitHub repository mendixlabs/mxcli (130 stars, last pushed yesterday), licensed Apache-2.0. It adds 56 tokens to every session and 8,607 once invoked, about $0.0002 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 2026-08-30.
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