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/xpath-constraintsWrote 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/xpath-constraints)<a href="https://agentmods.dev/skills/mendixlabs/mxcli/xpath-constraints"><img src="https://agentmods.dev/badge/skills/mendixlabs/mxcli/xpath-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/skills/mendixlabs/mxcli/xpath-constraints"><img src="https://agentmods.dev/badge/skills/mendixlabs/mxcli/xpath-constraints.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00042 | $0.04083 |
| Opus 5.5 | $0.00017 | $0.01633 |
| Sonnet 5.5 | $0.00008 | $0.00817 |
| Haiku 4.5 | $0.00004 | $0.00408 |
Grade A, and why
xpath-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 5d 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 — 434 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 |
|---|---|
| 28-34 | When to Use This Skill |
| 35-75 | XPath vs Mendix Expressions |
| 76-119 | Syntax Reference |
| 120-278 | How a Constraint Is Laid Out on Disk |
| 279-329 | Usage Contexts |
| 330-369 | Enumeration Attributes |
| 370-411 | Common Patterns |
| 412-423 | Validation |
| 424-433 | Troubleshooting |
XPath Constraints in MDL
This skill provides reference for writing XPath constraint expressions in MDL RETRIEVE statements, page data sources, and security rules.
When to Use This Skill
- Writing
retrieve ... where [xpath]statements in microflows - Writing
database from entity where [xpath]in page data sources - Writing
grant ... where 'xpath'for row-level entity access - Debugging XPath parsing or serialization issues
XPath vs Mendix Expressions
Critical distinction: XPath constraints (inside [...]) use different syntax from Mendix expressions (in SET, IF, DECLARE, etc.):
| Feature | XPath [...] |
Mendix Expression |
|---|---|---|
| Path separator | / (always path traversal) |
/ (also division) |
| Boolean ops | lowercase: and, or, not() |
and, or, not |
| Negation | not(expr) function |
not expr |
| Empty check | = empty, != empty |
= empty |
| Token quoting | '[%CurrentUser%]' (quoted) |
[%CurrentUser%] (unquoted) |
| Nested filter | Assoc/entity[pred] |
Not applicable |
| Arithmetic on value | not supported — pre-compute into a variable | +, -, *, div, mod |
XPath constraints cannot compute values.
where [Seq = $Game/MoveSeq + 1]is a parse error (Mendix XPath has no arithmetic on the value side). Compute the value first, then compare against the variable:declare $Next integer = $Game/MoveSeq + 1; retrieve $M from Mod.Move where [Seq = $Next] first;
mxcli checkexplains this and shows the workaround when it sees+/*/div/modinside a constraint.
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.
- 5d ago Changed · +18 lines 1ffba3ef98aa
- 9d ago Changed · +3 lines dc3d3819c335
- 14d ago Changed · +7 lines 28b0af5b391c
- 15d ago Changed · +2 lines eccec5aef43d
- 16d ago Changed · +1 lines 4e7a0f548e45
- 1mo ago Changed · +9 lines 6c1fbce3fce5
- 1mo ago First seen · 394 lines · 42 tokens per session scan A 12778bc6a46e
xpath-constraints is a skill published in the GitHub repository mendixlabs/mxcli (131 stars, last pushed yesterday), licensed Apache-2.0. It adds 42 tokens to every session and 4,083 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 2026-09-03.
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