Claude Skill

dotnet-meziantou-analyzer

Use the open-source free `Meziantou.Analyzer` package for design, usage, security, performance, and style rules in .NET. Use when a repo wants broader analyzer coverage with a single NuGet package.

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Part of postpartum-genushyacinthus29/dotnet-skills — 80 skills

Install

skills CLI npx skills add https://github.com/Postpartum-genushyacinthus29/dotnet-skills/tree/main/skills/dotnet-meziantou-analyzer
Claude Code claude plugin marketplace add https://llmmart.ai/marketplace.json && claude plugin install postpartum-genushyacinthus29-dotnet-skills@llmmart
Git git clone https://github.com/Postpartum-genushyacinthus29/dotnet-skills.git

The skills CLI installs just this skill, for any of its supported agents. Claude Code installs the whole postpartum-genushyacinthus29/dotnet-skills collection as a plugin from our marketplace. Git is the plain clone.

Skill manifest

Meziantou.Analyzer

Trigger On

  • the repo uses or wants Meziantou.Analyzer
  • the team wants one analyzer pack that covers design, usage, security, performance, and style

Value

  • produce a concrete project delta: code, docs, config, tests, CI, or review artifact
  • reduce ambiguity through explicit planning, verification, and final validation skills
  • leave reusable project context so future tasks are faster and safer

Do Not Use For

  • repos that already enforce an overlapping analyzer baseline and do not want extra diagnostics
  • formatting-only work

Inputs

  • the nearest AGENTS.md
  • current analyzer packages
  • .editorconfig

Quick Start

  1. Read the nearest AGENTS.md and confirm scope and constraints.
  2. Run this skill's Workflow through the Ralph Loop until outcomes are acceptable.
  3. Return the Required Result Format with concrete artifacts and verification evidence.

Workflow

  1. Add Meziantou.Analyzer when the repo wants broader rules than the SDK baseline.
  2. Keep rule severity in the repo-root .editorconfig.
  3. Review overlaps with SDK analyzers and Roslynator before mass-enabling everything as errors.

Bootstrap When Missing

If Meziantou.Analyzer is not configured yet:

  1. Detect current state:
    • rg -n "Meziantou\\.Analyzer" -g '*.csproj' .
  2. Add the package to the intended scope (project-level or shared props strategy):
    • dotnet add PROJECT.csproj package Meziantou.Analyzer
  3. Set severity in root .editorconfig for the enabled MAxxxx rules.
  4. Keep overlap with SDK analyzers and Roslynator explicit to avoid duplicate noise.
  5. Run dotnet build SOLUTION_OR_PROJECT and return status: configured or status: improved.
  6. If the repo intentionally keeps a smaller analyzer surface, return status: not_applicable.

Deliver

  • explicit Meziantou package setup
  • repo-owned severity and warning policy

Validate

  • the added rules are understood by the team
  • CI runs stay actionable instead of noisy

Ralph Loop

Use the Ralph Loop for every task, including docs, architecture, testing, and tooling work.

  1. Plan first (mandatory):
    • analyze current state
    • define target outcome, constraints, and risks
    • write a detailed execution plan
    • list final validation skills to run at the end, with order and reason
  2. Execute one planned step and produce a concrete delta.
  3. Review the result and capture findings with actionable next fixes.
  4. Apply fixes in small batches and rerun the relevant checks or review steps.
  5. Update the plan after each iteration.
  6. Repeat until outcomes are acceptable or only explicit exceptions remain.
  7. If a dependency is missing, bootstrap it or return status: not_applicable with explicit reason and fallback path.

Required Result Format

  • status: complete | clean | improved | configured | not_applicable | blocked
  • plan: concise plan and current iteration step
  • actions_taken: concrete changes made
  • validation_skills: final skills run, or skipped with reasons
  • verification: commands, checks, or review evidence summary
  • remaining: top unresolved items or none

For setup-only requests with no execution, return status: configured and exact next commands.

Load References

  • references/meziantou-analyzer.md
  • references/rules.md
  • references/config.md

Example Requests

  • "Add Meziantou analyzers to the repo."
  • "Use Meziantou for extra quality and security checks."
Files (dotnet-skills)
  • references
    • config.md 5.4 KB 
      # Meziantou.Analyzer EditorConfig Configuration

## Basic Setup

Add configuration to the root `.editorconfig` file to control rule severities.

### Severity Levels

- `none` - Disable the rule
- `silent` - Hidden from user, still runs
- `suggestion` - Shows as info message
- `warning` - Shows as warning
- `error` - Shows as error, fails build

## Recommended Starter Configuration

```ini
[*.cs]
# === Meziantou.Analyzer Configuration ===

# String handling - enforce explicit culture
dotnet_diagnostic.MA0001.severity = warning
dotnet_diagnostic.MA0002.severity = warning
dotnet_diagnostic.MA0006.severity = warning
dotnet_diagnostic.MA0011.severity = warning
dotnet_diagnostic.MA0074.severity = warning
dotnet_diagnostic.MA0076.severity = warning

# Async best practices
dotnet_diagnostic.MA0004.severity = warning
dotnet_diagnostic.MA0040.severity = warning
dotnet_diagnostic.MA0042.severity = warning
dotnet_diagnostic.MA0045.severity = warning
dotnet_diagnostic.MA0067.severity = warning

# Performance
dotnet_diagnostic.MA0005.severity = warning
dotnet_diagnostic.MA0020.severity = warning
dotnet_diagnostic.MA0028.severity = warning
dotnet_diagnostic.MA0029.severity = warning
dotnet_diagnostic.MA0031.severity = warning
dotnet_diagnostic.MA0063.severity = suggestion

# Design
dotnet_diagnostic.MA0015.severity = warning
dotnet_diagnostic.MA0025.severity = warning
dotnet_diagnostic.MA0047.severity = warning

# Security
dotnet_diagnostic.MA0014.severity = error
dotnet_diagnostic.MA0035.severity = error
dotnet_diagnostic.MA0055.severity = warning

# Regex
dotnet_diagnostic.MA0009.severity = suggestion
dotnet_diagnostic.MA0110.severity = suggestion

# Style - often project-specific
dotnet_diagnostic.MA0003.severity = none
dotnet_diagnostic.MA0026.severity = none
dotnet_diagnostic.MA0048.severity = none
dotnet_diagnostic.MA0051.severity = none
dotnet_diagnostic.MA0053.severity = none
```

## Library Configuration

Libraries should be stricter about async patterns and public API design:

```ini
[*.cs]
# Library-specific: require ConfigureAwait
dotnet_diagnostic.MA0004.severity = error

# Public API design
dotnet_diagnostic.MA0011.severity = error
dotnet_diagnostic.MA0015.severity = error
dotnet_diagnostic.MA0016.severity = error
dotnet_diagnostic.MA0018.severity = warning
```

## Application Configuration

Applications can be more relaxed about some rules:

```ini
[*.cs]
# Applications may not need ConfigureAwait
dotnet_diagnostic.MA0004.severity = none

# More relaxed on certain design rules
dotnet_diagnostic.MA0053.severity = suggestion
```

## Test Project Configuration

Test projects often need different rules:

```ini
[**/Tests/**/*.cs]
[**/Test/**/*.cs]
[**/*.Tests/**/*.cs]

# Disable sealed class requirement for test fixtures
dotnet_diagnostic.MA0053.severity = none

# Allow longer methods in tests
dotnet_diagnostic.MA0051.severity = none

# Allow TODO comments in tests
dotnet_diagnostic.MA0026.severity = none

# Tests may have blocking calls
dotnet_diagnostic.MA0042.severity = suggestion
dotnet_diagnostic.MA0045.severity = suggestion
```

## Generated Code Configuration

Exclude generated files from analysis:

```ini
[*.Generated.cs]
[*.g.cs]
[*.designer.cs]
generated_code = true
```

## Combining with Other Analyzers

When using Meziantou.Analyzer with other analyzers, avoid duplicate diagnostics:

### With Roslynator

```ini
# Roslynator RCS1197 overlaps with MA0020 (LINQ optimization)
# Pick one and disable the other
dotnet_diagnostic.RCS1197.severity = none
dotnet_diagnostic.MA0020.severity = warning

# Roslynator RCS1075 overlaps with MA0042 (async blocking)
dotnet_diagnostic.RCS1075.severity = none
dotnet_diagnostic.MA0042.severity = warning
```

### With StyleCop

```ini
# StyleCop SA1649 overlaps with MA0048 (file naming)
# Pick one and disable the other
dotnet_diagnostic.SA1649.severity = none
dotnet_diagnostic.MA0048.severity = warning
```

## Rule-Specific Options

Some Meziantou rules support additional configuration:

### MA0051 - Method Length

```ini
# Configure maximum method length
MA0051.maximum_lines_per_method = 60
MA0051.maximum_statements_per_method = 40
```

### MA0053 - Sealed Classes

```ini
# Configure when to suggest sealing
MA0053.public_class_should_be_sealed = true
```

## Migration Strategy

When adding Meziantou.Analyzer to an existing project:

### Phase 1: Start with suggestions

```ini
[*.cs]
dotnet_analyzer_diagnostic.category-Meziantou.severity = suggestion
```

### Phase 2: Gradually increase severity

```ini
[*.cs]
# Keep most as suggestions
dotnet_analyzer_diagnostic.category-Meziantou.severity = suggestion

# Promote critical rules to warnings
dotnet_diagnostic.MA0001.severity = warning
dotnet_diagnostic.MA0004.severity = warning
dotnet_diagnostic.MA0040.severity = warning
```

### Phase 3: Enforce in CI

```ini
[*.cs]
dotnet_analyzer_diagnostic.category-Meziantou.severity = warning

# Security rules as errors
dotnet_diagnostic.MA0014.severity = error
dotnet_diagnostic.MA0035.severity = error
```

## CI Integration

Build with warnings as errors for enforced rules:

```bash
dotnet build -warnaserror:MA0001,MA0004,MA0014,MA0035,MA0040
```

Or use the global setting:

```xml
<PropertyGroup>
  <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
</PropertyGroup>
```

## Sources

- [Meziantou.Analyzer Configuration](https://github.com/meziantou/Meziantou.Analyzer)
- [.editorconfig Documentation](https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/configuration-files)
    • meziantou-analyzer.md 769 B 
      # Meziantou.Analyzer

## Open/Free Status

- open source
- free to use

## Install

```bash
dotnet add package Meziantou.Analyzer
```

## Verify First

Before adding the package, check whether the repo already references it:

```bash
rg -n "Meziantou\\.Analyzer" -g '*.csproj' .
```

## Common Usage

```bash
dotnet build MySolution.sln -warnaserror
```

Configure severity in `.editorconfig`, for example:

```ini
[*.cs]
dotnet_diagnostic.MA0004.severity = warning
```

## CI Fit

- use `dotnet build` as the main enforcement gate
- keep severities explicit in repo config

## When Not To Use

- when the repo already decided the analyzer surface is intentionally smaller

## Sources

- [Meziantou.Analyzer repository](https://github.com/meziantou/Meziantou.Analyzer)
    • rules.md 4.4 KB 
      # Meziantou.Analyzer Rules

## Rule Categories

Meziantou.Analyzer organizes rules into several categories:

- **Design** - API design and architecture patterns
- **Usage** - Correct API usage and common pitfalls
- **Security** - Security best practices
- **Performance** - Performance optimizations
- **Style** - Code style and readability

## Commonly Used Rules

### Design Rules

| Rule ID | Description |
|---------|-------------|
| MA0004 | Use `ConfigureAwait(false)` in library code |
| MA0006 | Use `string.Equals` instead of `==` for case-insensitive comparisons |
| MA0011 | `IFormatProvider` is missing |
| MA0015 | Specify the parameter name in `ArgumentException` |
| MA0025 | Implement the functionality instead of throwing `NotImplementedException` |
| MA0026 | Fix TODO comment |
| MA0051 | Method is too long |
| MA0053 | Make class sealed |

### Usage Rules

| Rule ID | Description |
|---------|-------------|
| MA0001 | `StringComparison` is missing |
| MA0002 | `IEqualityComparer<string>` or `StringComparer` is missing |
| MA0003 | Add parameter name to improve readability |
| MA0005 | Use `Array.Empty<T>()` instead of a new empty array allocation |
| MA0009 | Add `RegexOptions.ExplicitCapture` to Regex |
| MA0010 | Mark attributes with `AttributeUsageAttribute` |
| MA0018 | Do not declare static members on generic types |
| MA0020 | Use direct methods instead of LINQ when available |

### Security Rules

| Rule ID | Description |
|---------|-------------|
| MA0007 | Add a comma after the last value |
| MA0008 | Add `StructLayoutAttribute` |
| MA0014 | Do not raise reserved exceptions |
| MA0035 | Do not use dangerous threading methods |
| MA0036 | Make class `static` |
| MA0055 | Do not use finalizer |
| MA0067 | Use `Task.FromResult` instead of creating a new `Task` |

### Performance Rules

| Rule ID | Description |
|---------|-------------|
| MA0028 | Optimize StringBuilder usage |
| MA0029 | Combine LINQ methods |
| MA0031 | Optimize `Enumerable.Count()` usage |
| MA0032 | Use an overload with a `StringComparer` parameter |
| MA0033 | Do not convert implicitly to `DateTimeOffset` |
| MA0040 | Forward the `CancellationToken` parameter to methods that take one |
| MA0041 | Make property static |
| MA0042 | Do not use blocking calls in an async method |
| MA0045 | Do not use blocking calls in an async method |
| MA0063 | Use `Where` before `OrderBy` |
| MA0110 | Use the `Regex` source generator |

### Style Rules

| Rule ID | Description |
|---------|-------------|
| MA0038 | Make method static |
| MA0043 | Use `nameof` operator |
| MA0047 | Declare types in namespaces |
| MA0048 | File name must match type name |
| MA0049 | Type should not implement `ToString()` with `IFormatProvider` parameter |
| MA0050 | Validate arguments correctly in iterator methods |
| MA0052 | Replace `Substring` with `Range` indexer |
| MA0076 | Do not use implicit culture-sensitive `ToString()` |

## High-Value Rules for New Projects

When starting a new project, consider enabling these rules as errors:

```ini
# Async best practices
dotnet_diagnostic.MA0004.severity = error
dotnet_diagnostic.MA0040.severity = error
dotnet_diagnostic.MA0042.severity = error

# String handling
dotnet_diagnostic.MA0001.severity = error
dotnet_diagnostic.MA0006.severity = error
dotnet_diagnostic.MA0011.severity = error

# Performance
dotnet_diagnostic.MA0005.severity = error
dotnet_diagnostic.MA0020.severity = error
dotnet_diagnostic.MA0029.severity = error

# Design
dotnet_diagnostic.MA0015.severity = error
dotnet_diagnostic.MA0053.severity = error
```

## Rules to Consider Disabling

Some rules may conflict with project style or be too strict:

| Rule ID | Reason to Disable |
|---------|-------------------|
| MA0003 | Parameter names may clutter simple method calls |
| MA0026 | TODO comments are valid during development |
| MA0051 | Method length thresholds may be too restrictive |
| MA0053 | Sealed classes may conflict with testing frameworks |
| MA0048 | File naming conventions may differ |

## Rule Interaction Notes

- MA0001 and MA0006 both deal with string comparisons; enable both for complete coverage
- MA0004 is essential for library code but can be disabled for application code
- MA0040, MA0042, and MA0045 all relate to async patterns; keep them aligned
- MA0020, MA0029, MA0031, and MA0063 overlap with LINQ optimization; configure consistently

## Sources

- [Meziantou.Analyzer Rules Documentation](https://github.com/meziantou/Meziantou.Analyzer/tree/main/docs/Rules)
  • SKILL.md 3.8 KB 
    ---
name: dotnet-meziantou-analyzer
version: "1.0.0"
category: "Code Quality"
description: "Use the open-source free `Meziantou.Analyzer` package for design, usage, security, performance, and style rules in .NET. Use when a repo wants broader analyzer coverage with a single NuGet package."
compatibility: "Requires a .NET SDK-based repository; respects the repo's `AGENTS.md` commands first."
---

# Meziantou.Analyzer

## Trigger On

- the repo uses or wants `Meziantou.Analyzer`
- the team wants one analyzer pack that covers design, usage, security, performance, and style

## Value

- produce a concrete project delta: code, docs, config, tests, CI, or review artifact
- reduce ambiguity through explicit planning, verification, and final validation skills
- leave reusable project context so future tasks are faster and safer

## Do Not Use For

- repos that already enforce an overlapping analyzer baseline and do not want extra diagnostics
- formatting-only work

## Inputs

- the nearest `AGENTS.md`
- current analyzer packages
- `.editorconfig`

## Quick Start

1. Read the nearest `AGENTS.md` and confirm scope and constraints.
2. Run this skill's `Workflow` through the `Ralph Loop` until outcomes are acceptable.
3. Return the `Required Result Format` with concrete artifacts and verification evidence.

## Workflow

1. Add `Meziantou.Analyzer` when the repo wants broader rules than the SDK baseline.
2. Keep rule severity in the repo-root `.editorconfig`.
3. Review overlaps with SDK analyzers and Roslynator before mass-enabling everything as errors.

## Bootstrap When Missing

If `Meziantou.Analyzer` is not configured yet:

1. Detect current state:
   - `rg -n "Meziantou\\.Analyzer" -g '*.csproj' .`
2. Add the package to the intended scope (project-level or shared props strategy):
   - `dotnet add PROJECT.csproj package Meziantou.Analyzer`
3. Set severity in root `.editorconfig` for the enabled `MAxxxx` rules.
4. Keep overlap with SDK analyzers and Roslynator explicit to avoid duplicate noise.
5. Run `dotnet build SOLUTION_OR_PROJECT` and return `status: configured` or `status: improved`.
6. If the repo intentionally keeps a smaller analyzer surface, return `status: not_applicable`.


## Deliver

- explicit Meziantou package setup
- repo-owned severity and warning policy

## Validate

- the added rules are understood by the team
- CI runs stay actionable instead of noisy

## Ralph Loop

Use the Ralph Loop for every task, including docs, architecture, testing, and tooling work.

1. Plan first (mandatory):
   - analyze current state
   - define target outcome, constraints, and risks
   - write a detailed execution plan
   - list final validation skills to run at the end, with order and reason
2. Execute one planned step and produce a concrete delta.
3. Review the result and capture findings with actionable next fixes.
4. Apply fixes in small batches and rerun the relevant checks or review steps.
5. Update the plan after each iteration.
6. Repeat until outcomes are acceptable or only explicit exceptions remain.
7. If a dependency is missing, bootstrap it or return `status: not_applicable` with explicit reason and fallback path.

### Required Result Format

- `status`: `complete` | `clean` | `improved` | `configured` | `not_applicable` | `blocked`
- `plan`: concise plan and current iteration step
- `actions_taken`: concrete changes made
- `validation_skills`: final skills run, or skipped with reasons
- `verification`: commands, checks, or review evidence summary
- `remaining`: top unresolved items or `none`

For setup-only requests with no execution, return `status: configured` and exact next commands.

## Load References

- `references/meziantou-analyzer.md`
- `references/rules.md`
- `references/config.md`

## Example Requests

- "Add Meziantou analyzers to the repo."
- "Use Meziantou for extra quality and security checks."

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