mtls-configuration

Configure mutual TLS (mTLS) for zero-trust service-to-service communication. Use when implementing zero-trust networking, certificate management, or securing internal service communication.

Quality

59%

Does it follow best practices?

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Securityby

Passed

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tessl review fix ./skills/mtls-configuration/SKILL.md

Quality

Content

39%Scale 1-5

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

The skill provides useful concrete YAML templates and debugging commands for mTLS configuration across multiple service mesh platforms, which is its primary strength. However, it suffers from being a large collection of templates without a coherent workflow, excessive verbosity in explaining concepts Claude already understands (mTLS flow, certificate hierarchy), and poor progressive disclosure with a broken reference to a non-existent bundle file. The lack of sequenced steps with validation checkpoints is particularly concerning for a security-critical configuration task.

Suggestions

Add a clear step-by-step workflow (e.g., '1. Deploy cert-manager → 2. Configure CA → 3. Apply PeerAuthentication → 4. Verify mTLS is active → 5. Switch to STRICT') with explicit validation commands between each step.

Remove the 'Core Concepts' section (mTLS flow diagram, certificate hierarchy) — Claude already knows these concepts. This would save ~30 lines of tokens.

Move the bulk YAML templates into separate bundle files (e.g., templates/istio-mtls.yaml, templates/spire-config.yaml) and reference them from SKILL.md with brief descriptions of when to use each.

Either create the referenced 'resources/implementation-playbook.md' bundle file or remove the broken reference, and replace the generic instructions ('Clarify goals, constraints...') with mTLS-specific actionable guidance.

Dimension	Reasoning	Score
Conciseness	The skill is significantly verbose. The ASCII diagrams explaining mTLS flow and certificate hierarchy are concepts Claude already knows. The 'Core Concepts' section, Do's/Don'ts best practices, and external resource links add bulk without providing novel actionable information. The templates themselves are useful but could be more targeted.	2 / 5
Actionability	The skill provides concrete, copy-paste ready YAML templates for Istio, Linkerd, cert-manager, and SPIRE configurations, plus executable bash commands for debugging and certificate rotation. Minor gaps include placeholder values like '<base64-encoded-ca-cert>' without guidance on generating them, and the generic instructions section ('Clarify goals, constraints...') is vague.	4 / 5
Workflow Clarity	There is no clear sequenced workflow for implementing mTLS end-to-end. Templates are presented as isolated snippets without a step-by-step process connecting them. There are no validation checkpoints between steps (e.g., verify mTLS is working after applying PeerAuthentication before proceeding to DestinationRules). For a security-critical operation like mTLS configuration, the lack of verification steps between stages is a significant gap.	2 / 5
Progressive Disclosure	The skill references 'resources/implementation-playbook.md' but no bundle files exist, making this a broken reference. The content is a monolithic wall of templates that would benefit from being split into separate files (e.g., istio-templates.md, spire-config.md, debugging.md). Over 250 lines of YAML templates are inlined with minimal navigation structure.	2 / 5
	Total	10 / 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 skill description that clearly communicates both purpose and trigger conditions. The 'Use when' clause with multiple trigger phrases is well-constructed. The main weakness is limited specificity—it could enumerate more concrete actions like certificate generation, rotation, or specific configuration tasks to better differentiate from generic TLS skills.

Suggestions

Add more specific actions such as 'generate client/server certificates, configure certificate rotation, set up certificate authorities, validate mTLS connections' to improve specificity.

Include additional trigger terms like 'client certificates', 'TLS authentication', 'service mesh security', or 'SPIFFE' to capture more natural user queries.

Dimension	Reasoning	Score
Specificity	Names the domain (mTLS, zero-trust networking) and describes a concrete action ('Configure mutual TLS for zero-trust service-to-service communication'), but lacks additional specific actions like certificate generation, rotation, revocation, or specific tooling details.	3 / 5
Completeness	Clearly answers both 'what' (configure mutual TLS for zero-trust service-to-service communication) and 'when' (explicit 'Use when' clause with concrete trigger phrases: implementing zero-trust networking, certificate management, securing internal service communication).	5 / 5
Trigger Term Quality	Includes good natural keywords like 'mTLS', 'mutual TLS', 'zero-trust', 'certificate management', 'service-to-service communication'. Missing some common variations like 'client certificates', 'TLS authentication', 'cert pinning', or specific tools like 'SPIFFE/SPIRE'.	4 / 5
Distinctiveness Conflict Risk	Fairly distinct with specific focus on mTLS and zero-trust service-to-service communication. Minor overlap risk with general TLS/SSL skills or broader certificate management skills, but the mTLS and zero-trust focus narrows it well.	4 / 5
	Total	16 / 20 Passed

Validation

90%

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 — 10 / 11 Passed

Validation for skill structure

Criteria	Description	Result
frontmatter_unknown_keys	Unknown frontmatter key(s) found; consider removing or moving to metadata	Warning

	Total	10 / 11 Passed

Repository: administrakt0r/AI-Agents-Safe-Coding-Skills
Path: skills/mtls-configuration/SKILL.md
Commit: fbdfd63

Reviewed: 1 day ago

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