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 Impertio-Studio/QGIS-Claude-Skill-Package --skill qgis-syntax-expressionsgit clone --depth 1 https://github.com/Impertio-Studio/QGIS-Claude-Skill-PackageWrote 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/impertio-studio/qgis-claude-skill-package/qgis-syntax-expressions)<a href="https://agentmods.dev/skills/impertio-studio/qgis-claude-skill-package/qgis-syntax-expressions"><img src="https://agentmods.dev/badge/skills/impertio-studio/qgis-claude-skill-package/qgis-syntax-expressions/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/impertio-studio/qgis-claude-skill-package/qgis-syntax-expressions"><img src="https://agentmods.dev/badge/skills/impertio-studio/qgis-claude-skill-package/qgis-syntax-expressions.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00091 | $0.02667 |
| Opus 5 | $0.00046 | $0.01333 |
| Sonnet 5 | $0.00018 | $0.00533 |
| Haiku 4.5 | $0.00009 | $0.00267 |
Grade A, and why
qgis-syntax-expressions 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 12d 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 — 296 lines — stays where its author put it; the contents beside it link to each section on GitHub.
qgis-syntax-expressions
Quick Reference
Expression Evaluation Pipeline
| Step | Class | Purpose |
|---|---|---|
| 1. Parse | QgsExpression(string) |
Validate syntax, build AST |
| 2. Context | QgsExpressionContext() |
Provide variables, fields, scopes |
| 3. Scopes | QgsExpressionContextUtils |
Add global/project/layer/feature scopes |
| 4. Evaluate | exp.evaluate(context) |
Execute and return result |
| 5. Validate | exp.hasEvalError() |
Check for runtime errors |
Expression Syntax Cheatsheet
| Element | Syntax | Example |
|---|---|---|
| Field reference | "field_name" (double quotes) |
"population" |
| String literal | 'text' (single quotes) |
'hello world' |
| Number literal | 123, 3.14 |
42 |
| NULL check | IS NULL, IS NOT NULL |
"name" IS NOT NULL |
| Comparison | =, !=, >, >=, <, <= |
"area" > 100 |
| Logical | AND, OR, NOT |
"pop" > 1000 AND "type" = 'city' |
| Arithmetic | +, -, *, /, ^, % |
"population" * 1.05 |
| Pattern match | LIKE, ILIKE, ~ (regex) |
"name" ILIKE '%lake%' |
| Concatenation | || |
"first" || ' ' || "last" |
| Conditional | CASE WHEN ... THEN ... END |
CASE WHEN "pop" > 1e6 THEN 'large' ELSE 'small' END |
| Geometry vars | $area, $length, $x, $y |
$area / 1e6 |
| Current geometry | $geometry |
num_points($geometry) |
Common Expression Functions
| Category | Functions |
|---|---|
| Math | sqrt(), abs(), round(), floor(), ceil(), sin(), cos(), pi() |
| String | upper(), lower(), length(), trim(), replace(), regexp_replace(), substr(), left(), right() |
| Conversion | to_int(), to_real(), to_string(), to_date(), to_datetime() |
| Date/Time | now(), day(), month(), year(), hour(), minute(), age(), day_of_week() |
| Geometry | $area, $length, $x, $y, $perimeter, centroid(), buffer(), area(), length(), num_geometries(), num_points() |
| Aggregates | aggregate(), sum(), count(), mean(), min(), max(), concatenate(), array_agg() |
| Conditionals | if(), coalesce(), nullif(), try() |
| Arrays | array(), array_length(), array_contains(), array_append(), array_to_string() |
| Map/Record | map(), map_get(), hstore_to_map() |
| Color | color_rgb(), color_hsv(), ramp_color(), darker(), lighter() |
What ships with it
3 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.
- 12d ago First seen · 296 lines · 91 tokens per session scan A 8de5490baaa2
qgis-syntax-expressions is a skill published in the GitHub repository Impertio-Studio/QGIS-Claude-Skill-Package (33 stars, last pushed 2mo ago), licensed MIT. It adds 91 tokens to every session and 2,667 once invoked, about $0.0005 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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