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n8n-expression-syntax

Validate n8n expression syntax and fix common errors. Use when writing n8n expressions, using {{}} syntax, accessing $json/$node variables, troubleshooting expression errors, or working with webhook data in workflows.

59

Quality

70%

Does it follow best practices?

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tessl review fix ./plugins/AI-Agents-Safe-Coding-Skills-claude/skills/n8n-expression-syntax/SKILL.md

The canonical home for this skill is n8n-expression-syntax in administrakt0r/AI-Agents-Safe-Coding-Skills

SKILL.md
Quality
Evals
Security

Quality

Content

50%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

The skill provides solid, actionable reference material for n8n expression syntax with good correct/incorrect examples and realistic scenarios. However, it is significantly bloated by repetition (webhook .body access, {{}} rules, and Code node warnings are each stated 3-4 times) and by including reference material Claude already knows (JavaScript string/array methods). The content would benefit from aggressive deduplication and splitting detailed reference material into bundle files.

Suggestions

Eliminate redundancy: the webhook .body rule, {{}} requirement, and Code node warning each appear 3-4 times — state each once in a dedicated section and remove duplicates from Summary, Best Practices, Validation Rules, and Common Mistakes.

Remove the 'Expression Helpers' section listing standard JavaScript methods (toLowerCase, map, filter, etc.) — Claude already knows these.

Move 'Data Type Handling', 'Advanced Patterns', and 'Expression Helpers' into a separate REFERENCE.md bundle file to keep SKILL.md as a concise overview.

Add an explicit validation workflow: describe how to actually validate expressions using the MCP tools mentioned in the description, with a check → fix → re-check loop.

DimensionReasoningScore

Conciseness

The skill is significantly verbose at ~350+ lines. It repeats the same concepts multiple times (webhook .body access is explained at least 4 separate times, the {{}} rule is stated repeatedly, Code node warnings appear multiple times). The Summary section largely restates what was already covered. The 'Expression Helpers' section lists standard JavaScript methods Claude already knows. The 'Best Practices' section is entirely redundant with prior content.

2 / 5

Actionability

The skill provides concrete, executable expression syntax with clear correct/incorrect examples throughout. The working examples with realistic JSON payloads are particularly useful. Minor gap: no actual validation commands or tool invocations are shown despite the skill description mentioning 'validate n8n expression syntax' — the debugging section is vague ('click fx icon').

4 / 5

Workflow Clarity

This is primarily a reference/syntax skill rather than a multi-step workflow, so the bar is lower. However, the skill description says 'Validate n8n expression syntax and fix common errors' which implies a validation workflow. The debugging section provides a rough sequence (open editor → check preview → look for errors) but lacks explicit validation checkpoints or a fix-and-retry loop. For a skill focused on validation and fixing, this is a gap.

3 / 5

Progressive Disclosure

References to COMMON_MISTAKES.md and EXAMPLES.md are appropriate and clearly signaled, but no bundle files are provided so these references are unverifiable. The main file itself contains too much content that could be split out — the Expression Helpers section, Data Type Handling, and Advanced Patterns would be better as separate reference files. The inline content is too long for an overview document.

3 / 5

Total

12

/

20

Passed

Description

89%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

This is a strong skill description with excellent trigger term coverage and completeness. The 'Use when' clause is well-constructed with multiple specific scenarios that map to natural user queries. The only minor weakness is that the 'what' portion could list more specific capabilities beyond 'validate' and 'fix common errors'.

DimensionReasoningScore

Specificity

Names the domain (n8n expressions) and two concrete actions (validate syntax, fix errors), but doesn't elaborate on the range of specific capabilities like what kinds of fixes, transformations, or validations it performs.

3 / 5

Completeness

Clearly answers both 'what' (validate n8n expression syntax and fix common errors) and 'when' (explicit 'Use when' clause with multiple concrete trigger scenarios like writing expressions, using {{}} syntax, accessing variables, troubleshooting errors, working with webhook data).

5 / 5

Trigger Term Quality

Excellent coverage of natural trigger terms including 'n8n expression', '{{}} syntax', '$json/$node variables', 'expression errors', 'webhook data', and 'workflows' — these are exactly the terms a user working with n8n would naturally use.

5 / 5

Distinctiveness Conflict Risk

Highly distinctive with a clear niche — n8n expression syntax is a very specific domain. The trigger terms like '$json/$node variables', '{{}} syntax', and 'n8n' are unlikely to conflict with any other skill.

5 / 5

Total

18

/

20

Passed

Validation

81%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation9 / 11 Passed

Validation for skill structure

CriteriaDescriptionResult

skill_md_line_count

SKILL.md is long (519 lines); consider splitting into references/ and linking

Warning

frontmatter_unknown_keys

Unknown frontmatter key(s) found; consider removing or moving to metadata

Warning

Total

9

/

11

Passed

Repository
administrakt0r/AI-Agents-Safe-Coding-Skills
Reviewed

Table of Contents

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