effective-go

effective-go

Claude Code plugin that makes Claude write architecturally tasteful Go -- not just code that compiles, but code a senior Go developer would approve of.

Install

claude plugin marketplace add https://github.com/williavs/effective-go-plugin
claude plugin install effective-go

Or manually:

git clone https://github.com/williavs/effective-go-plugin ~/.claude/plugins/effective-go

The Problem

Claude writes Go that compiles and runs but reads like translated Java. The syntax is fine -- formatting, naming, error handling all work. What's missing is architectural taste: zero-value types, small consumer-defined interfaces, composition via embedding, typed constants instead of raw strings.

What the Skill Teaches

Five things Claude doesn't naturally do in Go:

1. Zero-value design -- make var x T usable without a constructor
2. Consumer-defined interfaces -- 1-2 method interfaces defined where they're used, not where they're implemented
3. Composition via embedding -- promote methods instead of wrapping them
4. Typed constants -- named types for closed value sets, never raw strings
5. Standard library first -- sort.Slice, not hand-rolled loops

Results

We tested by running two Claude Code sessions side-by-side building the same apps. One had the skill, one didn't.

Headline finding: A non-coder typing a vague prompt with the skill produces better Go architecture than a detailed CS-dev spec without it.

	Skill + vague prompt	No skill + detailed spec
Interfaces	2 small (1-2 methods)	1 fat (4 methods)
Typed constants	4	0
go vet clean	Yes	No

The skill embeds senior engineer taste into every Go request, regardless of who's prompting.

See benchmarks/BENCHMARK.md for full methodology and data.

How We Got Here

This skill went through 5 iterations of testing:

1. V1 -- Pattern checklist (300 lines). Listed every Effective Go rule. Marginal improvement -- Claude already knows Go syntax.
2. V2 -- Design thinking (280 lines). Taught the thinking process before coding. First time interfaces and zero-value design appeared in outputs.
3. V3 -- Hard rules added (300 lines). 8 concrete rules from deep code review of V2 outputs (no os.Exit outside main, no hand-rolled sorts, etc.).
4. V4 -- Anti-paralysis fix (290 lines). V3 caused "planning paralysis" on vague prompts -- too much design thinking, not enough coding. Fixed the framing.
5. V5 -- Lean (120 lines). Removed everything Claude already does well. Kept only the 5 blind spots. The biggest improvement came from cutting the skill in half. Confirmed by Anthropic's own guidance: "every token added depletes Claude's attention budget."

Each iteration was tested with deterministic analysis: compilation, go vet, grep-based anti-pattern detection, interface counting. No LLM grading.

What's Included

Component	Description
skills/effective-go/SKILL.md	The skill (auto-triggers on Go code)
skills/effective-go/references/	Full Effective Go pattern reference
skills/effective-go/scripts/analyze.sh	Deterministic Go code analyzer (JSON output)
agents/go-reviewer.md	On-demand code review agent
benchmarks/	Raw experiment data

License

MIT