implement-posix-command

Implement a new POSIX command as a builtin in the safe shell interpreter

Quality

—

Does it follow best practices?

Impact

—

No eval scenarios have been run

Securityby

Advisory

Suggest reviewing before use

Quality

Content

77%

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

The content is exceptionally actionable with executable code and a rigorously gated, well-validated multi-step workflow. Its main weakness is that it is a long monolithic file with no progressive disclosure via reference files, which also drags conciseness down.

Suggestions

Move the reusable Go test-helper source, the YAML scenario schema, and the fuzz-seed catalogue into reference files (e.g. references/test-helpers.go.md, references/scenario-format.md) and link to them from the body.

Tighten the Step 4 and Step 9 prose by replacing explanatory sentences with compact checklists now that the boilerplate lives in references.

Add a short 'Quick reference' section near the top pointing to each step and each reference file so navigation is one level deep.

Dimension	Reasoning	Score
Conciseness	The body is dense and mostly actionable, but at roughly 600 lines it includes explanatory prose and reusable boilerplate (full test-helper source, YAML schema, fuzz-seed catalogues) that could be tightened or offloaded; it fits 'mostly efficient but could be tightened' rather than the lean level-3 anchor.	2 / 3
Actionability	It provides fully executable, copy-paste-ready Go code (runScript/cmdRun helpers, fuzz harness, test examples), exact shell commands, a concrete YAML scenario schema, and specific file paths, matching the 'fully executable code/commands' anchor.	3 / 3
Workflow Clarity	Ten explicitly sequenced steps with TaskList gate checks, defined parallel/sequential ordering, re-run-tests feedback loops, a second-pass independent review, and per-step completion criteria match 'clear sequence with explicit validation steps and feedback loops for error recovery'.	3 / 3
Progressive Disclosure	No bundle files exist and the entire skill is a single monolithic document with everything inline; while internal sectioning is good, content that should be separate (test helpers, YAML schema, fuzz-corpus guidance) is not split into reference files, fitting the 'content that should be separate is inline' anchor rather than level 3.	2 / 3
	Total	10 / 12 Passed

Description

57%

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

The description identifies a clear, distinct niche and a concrete action, but it is a single-action statement with no 'Use when...' trigger guidance and only modest trigger-term coverage. Adding explicit trigger phrasing and a fuller action list would raise it.

Suggestions

Append an explicit trigger clause, e.g. 'Use when adding a new POSIX command (cat, tail, head, sort) to the safe shell interpreter as a Go builtin.'

List multiple concrete actions (e.g. research the command, scaffold tests from GNU/uutils suites, implement the builtin, harden and fuzz-test it) to lift specificity to level 3.

Add natural trigger variations users would say, such as 'POSIX command', 'coreutils builtin', 'shell interpreter command'.

Dimension	Reasoning	Score
Specificity	The phrase 'Implement a new POSIX command as a builtin in the safe shell interpreter' names a concrete domain and one action ('implement'), but lists only a single action rather than multiple specific concrete actions, so it does not reach the level-3 anchor.	2 / 3
Completeness	It states clearly what the skill does but provides no 'when should Claude use it' guidance, and the missing 'Use when...' clause caps completeness at 2 per the judging guidelines.	2 / 3
Trigger Term Quality	Terms like 'POSIX command', 'builtin', and 'shell interpreter' are reasonably natural, but coverage is thin with no common variations or 'Use when' phrasing, fitting the 'some relevant keywords but missing common variations' anchor.	2 / 3
Distinctiveness Conflict Risk	The niche is precise — implementing POSIX commands as builtins inside a specific 'safe shell interpreter' — making it clearly distinguishable and unlikely to trigger for the wrong skill.	3 / 3
	Total	9 / 12 Passed

Validation

87%

Warnings & errors only

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

Validation — 14 / 16 Passed

Validation for skill structure

Criteria	Description	Result
skill_md_line_count	SKILL.md is long (611 lines); consider splitting into references/ and linking	Warning
frontmatter_unknown_keys	Unknown frontmatter key(s) found; consider removing or moving to metadata	Warning

	Total	14 / 16 Passed

Repository: DataDog/rshell
Commit: a0a1140

Reviewed: about 16 hours ago

Table of Contents

Discovery Implementation Validation

Is this your skill?

If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.