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spec-driven-development

Creates specs before coding. Use when starting a new project, feature, or significant change and no specification exists yet. Use when requirements are unclear, ambiguous, or only exist as a vague idea.

83

1.90x
Quality

76%

Does it follow best practices?

Impact

95%

1.90x

Average score across 3 eval scenarios

SecuritybySnyk

Passed

No findings from the security scan

Fix and improve this skill with Tessl

tessl review fix ./skills/spec-driven-development/SKILL.md

The canonical home for this skill is spec-driven-development in addyosmani/agent-skills

SKILL.md
Quality
Evals
Security

Quality

Content

73%Scale 1-5

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 process skill with clear gated workflows, concrete templates, and good cross-references to related skills. Its main weakness is verbosity — the motivational content (rationalizations table, red flags, explanatory prose about why specs matter) adds ~40 lines that Claude doesn't need. The actionable content (templates, examples, phase definitions) is strong and practical.

Suggestions

Remove or significantly trim the 'Common Rationalizations' table and 'Red Flags' section — Claude doesn't need to be convinced why specs are valuable, it needs to know how to write them.

Cut motivational framing like 'Code without a spec is guessing' and 'The spec's entire purpose is to surface misunderstandings' — these explain rationale Claude can infer from the workflow itself.

DimensionReasoningScore

Conciseness

The skill contains useful content but is notably verbose in places. The 'Common Rationalizations' table and 'Red Flags' section explain things Claude already understands about why specs matter. The assumptions example and reframing example are valuable, but the motivational framing ('Code without a spec is guessing') and several explanatory sentences could be trimmed. The spec template is appropriately detailed but the surrounding prose adds unnecessary justification.

3 / 5

Actionability

The skill provides concrete templates, specific examples (assumptions block, success criteria reframing, task template, spec template with all six areas), and executable command examples. However, it's more of a process/methodology skill than a code skill, so some guidance remains at the instructional level. The task template and spec template are copy-paste ready, and the phase descriptions give clear steps. Minor gap: the verification checklist at the end is good but could be more specific about how to validate each item.

4 / 5

Workflow Clarity

The four-phase gated workflow (Specify → Plan → Tasks → Implement) is clearly sequenced with an ASCII diagram. Each phase has explicit human review gates before advancing. The verification checklist at the end provides a concrete checkpoint. The workflow includes feedback loops (asking clarifying questions, surfacing assumptions for correction, reframing requirements for validation). This is a well-structured multi-step process with appropriate validation at each stage.

5 / 5

Progressive Disclosure

The skill appropriately references external skills (planning-and-task-breakdown, incremental-implementation, test-driven-development, context-engineering) with clear signaling about what each covers and explicit precedence rules. It also specifies output paths (tasks/plan.md, tasks/todo.md). However, there are no bundle files provided, so the references to skills/ paths can't be verified. The content is somewhat long (~180 lines) but most of it is templates and examples that belong inline. Minor gap: the Common Rationalizations table could arguably be in a separate reference file.

4 / 5

Total

16

/

20

Passed

Description

78%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 solid description with excellent completeness—it clearly states what the skill does and provides multiple explicit trigger conditions. Its main weakness is limited specificity about what 'creating specs' actually involves (e.g., does it produce a document, gather requirements, define APIs?). Trigger terms are good but could include more synonyms like 'design doc' or 'PRD'.

Suggestions

Add more specific actions that describe what the spec creation involves, e.g., 'Gathers requirements, defines scope, outlines architecture, and produces a written specification document'

Include additional trigger synonyms like 'design doc', 'PRD', 'technical spec', 'plan', or 'architecture' to improve discoverability

DimensionReasoningScore

Specificity

Names the domain (spec creation) and one concrete action ('Creates specs before coding'), but doesn't elaborate on what creating a spec entails—e.g., gathering requirements, defining architecture, writing acceptance criteria, etc.

3 / 5

Completeness

Clearly answers both 'what' (creates specs before coding) and 'when' (starting a new project/feature/significant change, no spec exists, requirements are unclear or ambiguous). The 'Use when' clauses are explicit and provide concrete trigger scenarios.

5 / 5

Trigger Term Quality

Includes natural terms like 'specs', 'new project', 'feature', 'requirements', 'vague idea', and 'specification'. Missing some synonyms like 'design doc', 'PRD', 'technical spec', 'plan', or 'architecture document'.

4 / 5

Distinctiveness Conflict Risk

Fairly distinct—spec creation before coding is a specific niche. Minor overlap risk with planning, architecture, or requirements-gathering skills, but the explicit triggers around 'no specification exists yet' and 'requirements are unclear' help differentiate it.

4 / 5

Total

16

/

20

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
finlay611/agent-skills
Reviewed

Table of Contents

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