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 skills add mendixlabs/mxcli --skill cheatsheet-errorsgit clone --depth 1 https://github.com/mendixlabs/mxcliWrote 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/cheatsheet-errors)<a href="https://agentmods.dev/skills/mendixlabs/mxcli/cheatsheet-errors"><img src="https://agentmods.dev/badge/skills/mendixlabs/mxcli/cheatsheet-errors/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/cheatsheet-errors"><img src="https://agentmods.dev/badge/skills/mendixlabs/mxcli/cheatsheet-errors.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 | $0.00052 | $0.02620 |
| Opus 5.5 | $0.00021 | $0.01048 |
| Sonnet 5.5 | $0.00010 | $0.00524 |
| Haiku 4.5 | $0.00005 | $0.00262 |
Grade A, and why
cheatsheet-errors 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 — 310 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 |
|---|---|
| 26-78 | Variable Errors |
| 79-130 | Expression Errors |
| 131-178 | Control Flow Errors |
| 179-216 | Syntax Errors |
| 217-281 | Reference Errors |
| 282-297 | Studio Pro Error Code Reference |
| 298-309 | Quick Validation Checklist |
MDL Common Errors Cheatsheet
Quick fixes for common MDL syntax errors.
Variable Errors
"Variable 'X' is not declared"
Problem: Using SET on a variable that wasn't declared.
-- WRONG
if $value > 10 then
set $IsValid = false; -- ERROR: $IsValid not declared
end if;
Fix: Add DECLARE before SET.
-- CORRECT
declare $IsValid boolean = true;
if $value > 10 then
set $IsValid = false;
end if;
"Selected type is not allowed" (CE0053)
Problem: Declaring an object (entity) or list variable. A declare maps to a
Create Variable activity, which only accepts primitives
(String/Integer/Long/Decimal/Boolean/DateTime/Enumeration). Declaring an object or
list is rejected (CE0053/CE0038, plus CE7247 on any later set) — bare or
initialized. The as keyword is also a parse error in mxcli. mxcli check flags an
object declare as MDL043 and a list declare as MDL040.
-- WRONG: declaring an object — there is no "empty object variable" (MDL043)
declare $Product Module.Product = empty;
declare $Product as Module.Product; -- AS is also a parse error
-- WRONG: declaring a list (MDL040)
declare $Products list of Module.Product = empty;
Fix: Objects and lists can't be declared — get them from a source that produces one.
-- object: a microflow parameter, a retrieve, a create, or a loop iterator
retrieve $Product from Module.Product where Code = $Code first; -- retrieve
$Product = create Module.Product (Name = $Name); -- create
-- or: create microflow M.Save ($Product: Module.Product) ... / loop $Product in $Products ...
-- list: a parameter, a retrieve, or a create list
$Products = create list of Module.Product; -- empty list to accumulate into
retrieve $Products from Module.Product where ...; -- or populate from the database
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 Changed · +6 lines 266df640eb4d
- 5d ago Changed · +16 lines 70f319488fab
- 8d ago Changed · +1 lines 098e95219929
- 15d ago Changed 5e81fe42d282
- 1mo ago Changed · +2 lines fac7d09863ad
- 1mo ago First seen · 285 lines · 52 tokens per session scan A 0fd51e2baccf
cheatsheet-errors is a skill published in the GitHub repository mendixlabs/mxcli (130 stars, last pushed yesterday), licensed Apache-2.0. It adds 52 tokens to every session and 2,620 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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