Catalog
getsentry/skill-writer

getsentry

skill-writer

Create, synthesize, and iteratively improve agent skills following the Agent Skills specification. Use when asked to "create a skill", "write a skill", "synthesize sources into a skill", "improve a skill from positive/negative examples", "update a skill", or "maintain skill docs and registration". Handles source capture, precision passes, authoring, registration, and validation.

NewUpdated Sep 9, 2026

Skill Writer

Use this as the single canonical workflow for skill creation and improvement. Primary success condition: maximize high-value input coverage before authoring while minimizing wasted runtime tokens.

Follow the workflow steps in order. Load only the reference files required for the step you are on. SKILL.md is the primary router: every bundled reference file should be flat under references/ and listed here with a direct "open when..." reason.

Core Workflow References

Open when you need to... Read
choose the minimum workflow path for create, update, iterate, or research-first work references/mode-selection.md
choose the simplest adequate execution shape before deciding files references/execution-shapes.md
apply writing constraints for depth, concision, and portability references/design-principles.md
decide what belongs in SKILL.md, references/, SPEC.md, or supporting files references/reference-architecture.md
create or update the maintenance contract for a skill references/spec-template.md
find missing high-signal sources, including history and regressions references/source-discovery.md
adapt an upstream prompt, workflow, rubric, benchmark, or docs into a skill references/source-adaptation.md
run the full synthesis pass with coverage checks and source capture references/synthesis-path.md
author or update SKILL.md, SPEC.md, and supporting files references/authoring-path.md
improve trigger language and false-positive/false-negative behavior references/description-optimization.md
iterate from positive, negative, or fix examples references/iteration-path.md
store persistent working and holdout examples for future revisions references/iteration-evidence.md
choose a response template, schema, or output contract references/output-contracts.md
add or update evals for a skill's generated outputs or runtime behavior references/skill-evals.md
troubleshoot overloaded layouts, hidden refs, or other structure failures references/structure-troubleshooting.md
register the skill and run final validation checks references/registration-validation.md

Artifact Layout References

Open when you need to... Read
keep the whole skill inline in one coherent SKILL.md references/layout-inline-skill.md
split optional deep knowledge into focused routed references references/layout-reference-backed-skill.md
add scripts for deterministic automation or validation references/layout-script-backed-workflow.md
define a skill that is usually invoked with explicit arguments references/layout-argument-driven-skill.md
ship reusable templates, schemas, or other static assets references/layout-asset-template-skill.md

Workflow Mechanic References

Open when you need to... Read
break a task into fixed ordered steps references/workflow-prompt-chaining.md
classify requests and route them to different downstream paths references/workflow-routing.md
split independent work into parallel units or votes references/workflow-parallel.md
discover work units dynamically and coordinate worker outputs references/workflow-orchestrator-workers.md
run validate-fix-repeat checks during authoring or execution references/workflow-validation-loops.md
validate a plan before executing a risky action references/workflow-plan-validate-execute.md

Claude Code References

Open when you need to... Read
use Claude-specific frontmatter or invocation controls references/claude-frontmatter-invocation.md
use Claude argument fields or substitution variables references/claude-argument-substitutions.md
build a skill that runs in isolated context: fork references/claude-subagent-fork.md
build a skill that uses Claude hooks for deterministic enforcement references/claude-hook-backed.md
use Claude shell preprocessing for dynamic context injection references/claude-dynamic-context.md

Example Profiles

Open when you need to... Read
see the expected depth for a documentation-heavy skill references/example-documentation-skill.md
see the expected depth for a workflow-process skill references/example-workflow-process-skill.md
see what a good routed skill looks like references/example-router-skill.md
see what a good subagent-fork skill looks like references/example-subagent-fork-skill.md
see what a good hook-backed skill looks like references/example-hook-backed-skill.md

Step 1: Resolve target, path, and shape

  1. Resolve the intended operation (create, update, synthesize, iterate) and inspect workspace prior art before choosing where files belong.
  2. Choose the target skill root from observed conventions. If the canonical location is still unclear after inspection, ask one direct question before editing files.
  3. Read references/mode-selection.md to choose the minimum required workflow paths.
  4. Read references/execution-shapes.md to choose the primary execution shape.
  5. Default to the simplest adequate shape. If selecting a more complex shape, record why simpler shapes were rejected.
  6. Load only the exact artifact-layout, workflow-mechanic, and provider-specific leaf files required by that shape.
  7. Before adding guidance, identify what existing rule, section, or file should be narrowed, replaced, or removed.
  8. Record portability implications before using provider-specific mechanics.

Step 2: Run synthesis when needed

Read references/synthesis-path.md.

  1. Use this path for new skills, material changes, and research-first planning.
  2. Collect and score relevant sources with provenance.
  3. Read references/source-discovery.md when source material is thin, stale, or ambiguous.
  4. Read references/source-adaptation.md when adapting an upstream prompt, workflow, rubric, benchmark, or docs.
  5. Produce source-backed decisions and coverage/gap status, including the class and execution-shape choice.
  6. Load example profiles only when they add concrete depth for the selected class or shape.
  7. If the skill uses provider-specific mechanics, include current official provider docs and capture usage constraints.
  8. Do not move to authoring until required coverage is understood or gaps are explicit.

Step 3: Run iteration first when improving from outcomes/examples

Read references/iteration-path.md first when selected path includes iteration (for example operation iterate).

  1. Capture and anonymize examples with provenance.
  2. Read references/iteration-evidence.md when examples should persist beyond the current turn.
  3. Review skill behavior against working and holdout slices.
  4. Propose improvements from positive/negative/fix evidence.
  5. Carry concrete behavior deltas into authoring.

Skip this step when selected path does not include iteration.

Step 4: Author or update skill artifacts

Read references/authoring-path.md.

  1. Write or update SKILL.md in imperative voice with trigger-rich description.
  2. Keep SKILL.md as the runtime router, not an encyclopedia.
  3. Run the pre-edit precision check in references/authoring-path.md before creating new sections or files.
  4. Read references/reference-architecture.md before adding bulk instructions or new reference files.
  5. Create or update SPEC.md using references/spec-template.md when creating a new skill or materially changing its contract.
  6. Create focused reference files, scripts, and assets only when each one has a clear "open when..." reason and cannot be handled by tightening an existing file.
  7. If you add a bundled reference file, add a direct routing entry for it in this SKILL.md.
  8. Prefer checklists, tables, templates, and input/output examples over explanatory prose.
  9. Follow only the specific artifact-layout, workflow-mechanic, Claude-specific, and output-contract references selected for this skill.
  10. For advanced execution shapes, add the required routing, delegation, or safety contracts before considering the skill complete.
  11. For authoring/generator skills, include transformed examples in references:
  • happy-path
  • secure/robust variant
  • anti-pattern + corrected version
  1. Read references/skill-evals.md when the request asks for evals, regression cases, benchmark cases, or model-graded quality checks for the skill being authored.
  2. After any skill artifact changes, run the post-change precision pass in references/authoring-path.md before description optimization or validation.

Step 5: Optimize description quality

Read references/description-optimization.md.

  1. Validate should-trigger and should-not-trigger query sets.
  2. Reduce false positives and false negatives with targeted description edits.
  3. Keep trigger language generic across providers unless the skill is intentionally provider-specific.

Step 6: Register and validate

Read references/registration-validation.md.

  1. Apply repository registration steps for the active layout you verified in the workspace.
  2. Run quick validation for structural checks.
  3. Review validator warnings, precision-pass results, and coverage gaps with judgment before completion.

Output format

Return:

  1. Summary
  2. Changes Made
  3. Validation Results
  4. Open Gaps
Files46
46 files · 127.2 KB

Select a file to preview

Overall Score

84/100

Grade

B

Good

Grades are signals, not a certification. Always review a skill yourself before use.

Safety

82

Quality

87

Clarity

85

Completeness

80

Summary

The `skill-writer` skill is a meta-router for creating, updating, synthesizing, and iteratively improving agent skills in a repository. It guides users through explicit workflow paths (synthesis, authoring, iteration, description optimization, registration/validation) and emphasizes choosing the simplest adequate execution shape before deciding on artifacts. The skill is comprehensive, well-structured with flat routed references, and includes supporting infrastructure for validation and evaluation via AXIS. However, two static analysis findings require assessment: direct `.env` file access in reference documentation (SEC-020, low risk in context) and shell eval/exec patterns in skill-evals reference (SEC-011, medium risk requiring scrutiny).

Static Analysis Findings

2 findings

Patterns detected by deterministic static analysis before AI scoring. Hover over any finding code for detailed information and remediation guidance.

Credential Exposure
SEC-020Direct .env File Access

Direct .env file access

references/claude-hook-backed.md.env
Command Injection
SEC-011Dynamic Shell Eval

Shell eval/exec of dynamic content

references/skill-evals.mdexec`

Detected Capabilities

file readfile write (to skill directories)reference routingworkflow decision logicschema validationdocument structure analysistemplate generationscript execution (Python validator)

Trigger Keywords

Phrases that agents use to match this skill to user intent.

create a skillwrite a skillsynthesize skillimprove skillskill authoringskill structureroute referencesskill validationskill evaluationagent skill

Risk Signals

WARNING

SEC-020: Direct .env file access detected in `references/claude-hook-backed.md`

references/claude-hook-backed.md | Match: `.env` context
WARNING

SEC-011: Shell eval/exec of dynamic content in `references/skill-evals.md`

references/skill-evals.md | Match: command-injection and judge scenarios

Referenced Domains

External domains referenced in skill content, detected by static analysis.

agentskills.ioaxis.runcacm.acm.orgcode.claude.comdevelopers.openai.comdiataxis.frdita-lang.orggithub.comhuggingface.coopenai.comopenai.github.ioplatform.openai.comwww.anthropic.comwww.apache.orgwww.promptfoo.devwww.writethedocs.org

Use Cases

  • Create a new agent skill from sources
  • Update or improve an existing agent skill
  • Choose the correct execution shape for a skill
  • Synthesize upstream prompts or docs into a skill
  • Iterate on a skill from positive/negative examples
  • Write skill specifications and maintenance contracts
  • Route skill references for progressive disclosure
  • Register and validate skills in a repository
  • Design and run skill evaluation test cases
  • Debug skill structure or authoring decisions

Quality Notes

  • Excellent: Comprehensive meta-routing workflow with explicit class/shape selection before authoring prevents shallow skill creation.
  • Excellent: Flat routed reference architecture with clear 'open when...' reasons enables progressive disclosure and prevents `SKILL.md` bloat.
  • Excellent: Reference-architecture and design-principles guidance keeps runtime instructions dense (tables, checklists, examples over prose).
  • Excellent: Supporting infrastructure includes lightweight structural validator, source provenance tracking (SOURCES.md), and durable evidence storage (references/evidence/).
  • Excellent: Skill-evals guidance with AXIS as prescriptive open-source harness with concrete case format, baseline comparison, and judge scoring rubric.
  • Excellent: Precision-pass methodology ensures every change replaces/narrows/moves/deletes rather than accumulating guidance.
  • Good: Strong justification for simplicity-first design and explicit rejection of advanced mechanics without evidence.
  • Good: Portability guidance explicitly labels provider-specific mechanics and avoids generalizing Claude-specific behavior to portable defaults.
  • Good: SPEC.md serves as maintenance contract with explicit scope boundaries and known limitations.
  • Minor: SEC-020 in claude-hook-backed.md is reference material documenting a security constraint (.env should be avoided), not a directive to access .env files.
  • Minor: SEC-011 in skill-evals.md refers to using 'exec' in judging skill outputs (detecting if a generated skill uses eval), not instructing `skill-writer` to execute dynamic code at runtime.
  • Potential concern: Quick-validate.py allows arbitrary path traversal in referenced files (regex-based file discovery), but only warns/fails if files don't exist—not a direct vulnerability in skill-writer's execution.
Model: claude-haiku-4-5-20251001Analyzed: Sep 9, 2026

Reviews

Add this skill to your library to leave a review.

No reviews yet

Be the first to share your experience.

Version History

  1. v1.1

    Content updated

    ✦ AISupporting documentation updated; safety grade moved from A to B.

    2026-09-09

    LATEST
  2. v1.0

    2026-07-11

    View This VersionInitial version

Use getsentry/skill-writer in your dev environment

Command Palette

Search for a command to run...