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legacy-modernizer

Designs incremental migration strategies, identifies service boundaries, produces dependency maps and migration roadmaps, and generates API facade designs for aging codebases. Use when modernizing legacy systems, implementing strangler fig pattern or branch by abstraction, decomposing monoliths, upgrading frameworks or languages, or reducing technical debt without disrupting business operations.

72

Quality

88%

Does it follow best practices?

Impact

No eval scenarios have been run

SecuritybySnyk

Passed

No known issues

SKILL.md
Quality
Evals
Security

Quality

Content

77%

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

This is a well-structured skill with strong workflow clarity and actionable code examples. Its main weaknesses are the missing bundle files that the reference table points to, and some verbosity in the constraints and output templates sections that could be tightened. The core workflow with validation checkpoints is exemplary for a high-risk domain like legacy modernization.

Suggestions

Create the five referenced files (references/strangler-fig-pattern.md, etc.) to back the reference table, or remove the table if they won't be provided.

Trim the 'Knowledge Reference' keyword list and the 'Output Templates' section — replace with a concrete example of a migration plan output or remove entirely to save tokens.

DimensionReasoningScore

Conciseness

The skill is reasonably efficient but includes some unnecessary content. The 'Knowledge Reference' section at the bottom is just a keyword list that adds no actionable value. The MUST DO/MUST NOT DO lists contain items Claude already understands (e.g., 'Communicate progress and risks transparently'). The Output Templates section is vague and could be tightened.

2 / 3

Actionability

The skill provides fully executable Python code examples for the strangler fig facade, feature flags, and characterization tests. These are copy-paste ready, concrete, and directly illustrate the core patterns. The workflow steps include specific, measurable guidance (e.g., '80%+ coverage', traffic increment percentages).

3 / 3

Workflow Clarity

The 5-step workflow has explicit validation checkpoints at every stage, including feedback loops (e.g., 'fix and re-validate'), rollback triggers, and clear sequencing. The traffic increment progression (5% → 25% → 50% → 100%) and the requirement to prove stability at 100% before removing legacy code are excellent validation gates for this inherently risky operation.

3 / 3

Progressive Disclosure

The reference table is well-structured with clear 'Load When' guidance, providing good navigation signals. However, no bundle files were provided, meaning all five referenced files (strangler-fig-pattern.md, refactoring-patterns.md, etc.) are missing. The skill inlines substantial code examples that could arguably live in reference files, while the actual reference files that should contain detailed guidance don't exist.

2 / 3

Total

10

/

12

Passed

Description

100%

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 an excellent skill description that clearly articulates specific capabilities (migration strategies, service boundary identification, dependency maps, API facade designs) and provides comprehensive trigger guidance via an explicit 'Use when...' clause. The description uses appropriate third-person voice, includes domain-specific terms that practitioners would naturally use, and carves out a distinct niche around legacy system modernization.

DimensionReasoningScore

Specificity

Lists multiple specific concrete actions: 'designs incremental migration strategies', 'identifies service boundaries', 'produces dependency maps and migration roadmaps', and 'generates API facade designs for aging codebases'.

3 / 3

Completeness

Clearly answers both 'what' (designs migration strategies, identifies service boundaries, produces dependency maps, generates API facade designs) and 'when' with an explicit 'Use when...' clause listing multiple trigger scenarios.

3 / 3

Trigger Term Quality

Excellent coverage of natural terms users would say: 'legacy systems', 'strangler fig pattern', 'branch by abstraction', 'decomposing monoliths', 'upgrading frameworks or languages', 'technical debt', 'migration', 'modernizing'. These are terms practitioners naturally use when facing these challenges.

3 / 3

Distinctiveness Conflict Risk

Occupies a clear niche around legacy system modernization and monolith decomposition. The specific mentions of strangler fig pattern, branch by abstraction, API facades, and dependency maps make it highly distinct and unlikely to conflict with general coding or architecture skills.

3 / 3

Total

12

/

12

Passed

Validation

100%

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

Validation11 / 11 Passed

Validation for skill structure

No warnings or errors.

Repository
Jeffallan/claude-skills
Reviewed

Table of Contents

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