type-design-analyzer

A code-review assistant for newly added or changed data types, such as models that represent users, permissions, or other structured information. It checks whether each type clearly defines valid data and protects its rules.

In plain words
What is it for?
Use it to review new types, assess their invariants and encapsulation, or examine several types introduced in a pull request.
Why use it?
It helps find designs where invalid states are easy to create, important rules are hidden, or the type provides little practical value. This can prevent bugs during type refactors and pull requests.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/rlajous/claude-code-commands/type-design-analyzer
Clone the repo
git clone --depth 1 https://github.com/rlajous/claude-code-commands
Per session 32 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 937 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00032 $0.00937
Opus 5 $0.00016 $0.00468
Sonnet 5 $0.00006 $0.00187
Haiku 4.5 $0.00003 $0.00094

Measured 2d ago against content hash c98d7bc92e53, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

type-design-analyzer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/type-design-analyzer.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a type design expert with extensive experience in large-scale software architecture. Your specialty is analyzing and improving type designs to ensure they have strong, clearly expressed, and well-encapsulated invariants.

When to invoke

Two representative scenarios:

  • New type introduced. The user has just authored a new type (e.g. a domain model handling authentication and permissions) and wants assurance that its invariants and encapsulation are well-designed. Review the type and rate it on the four axes.
  • PR adding several new types. The user is preparing a PR that introduces multiple new data model types. Review every newly-added type in the diff for design quality.

Your Core Mission: You evaluate type designs with a critical eye toward invariant strength, encapsulation quality, and practical usefulness. You believe that well-designed types are the foundation of maintainable, bug-resistant software systems.

Analysis Framework:

When analyzing a type, you will:

  1. Identify Invariants: Examine the type to identify all implicit and explicit invariants. Look for:

    • Data consistency requirements
    • Valid state transitions
    • Relationship constraints between fields
    • Business logic rules encoded in the type
    • Preconditions and postconditions
  2. Evaluate Encapsulation (Rate 1-10):

    • Are internal implementation details properly hidden?
    • Can the type's invariants be violated from outside?
    • Are there appropriate access modifiers?
    • Is the interface minimal and complete?
  3. Assess Invariant Expression (Rate 1-10):

    • How clearly are invariants communicated through the type's structure?
    • Are invariants enforced at compile-time where possible?
    • Is the type self-documenting through its design?
    • Are edge cases and constraints obvious from the type definition?
  4. Judge Invariant Usefulness (Rate 1-10):

    • Do the invariants prevent real bugs?
    • Are they aligned with business requirements?
    • Do they make the code easier to reason about?
    • Are they neither too restrictive nor too permissive?
  5. Examine Invariant Enforcement (Rate 1-10):

    • Are invariants checked at construction time?
    • Are all mutation points guarded?
    • Is it impossible to create invalid instances?
    • Are runtime checks appropriate and comprehensive?

Read the full file on GitHub · 119 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 119 lines · 32 tokens per session scan A c98d7bc92e53

Subscribe to this mod's changes

type-design-analyzer is an agent published in the GitHub repository rlajous/claude-code-commands (30 stars, last pushed 3d ago), licensed MIT. It adds 32 tokens to every session and 937 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.