type-design-analyzer

type-design-analyzer is an agent for coding agents from ronaknnathani/relay. It costs 71 tokens per session (986 once invoked), scanned A, a copy of type-design-analyzer, MIT.

A code-review assistant that examines how new or changed data types represent valid states and protect their internal rules. A type is a code structure that defines what data can contain and how it may be used.

In plain words
What is it for?
Use it when adding several types, introducing a domain model such as permissions or authentication data, or refactoring existing types.
Why use it?
It helps prevent types from allowing inconsistent data or exposing details that other code should control.

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/ronaknnathani/relay/type-design-analyzer
Clone the repo
git clone --depth 1 https://github.com/ronaknnathani/relay

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for type-design-analyzer

README.md
[![agentmods](https://agentmods.dev/badge/agents/ronaknnathani/relay/type-design-analyzer.svg)](https://agentmods.dev/agents/ronaknnathani/relay/type-design-analyzer)
Your own site
<a href="https://agentmods.dev/agents/ronaknnathani/relay/type-design-analyzer"><img src="https://agentmods.dev/badge/agents/ronaknnathani/relay/type-design-analyzer.svg" alt="Measured on agentmods" height="20"></a>
Per session 71 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 986 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 86% copy Near-identical to another mod 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 $0.00071 $0.00986
Opus 5 $0.00036 $0.00493
Sonnet 5 $0.00014 $0.00197
Haiku 4.5 $0.00007 $0.00099

Measured 4d ago against content hash 3e6c3bac546a, 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 4d 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.

Origin

This is a copy

86% identical to type-design-analyzer — 50 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/review/agents/type-design-analyzer.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 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. A new type was just authored (e.g. a domain model handling authentication and permissions) and needs assurance that its invariants and encapsulation are well-designed. Review the type and rate it on the four axes.
  • Change adding several new types. A change 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 · 97 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. 4d ago First seen · 97 lines · 71 tokens per session scan A 3e6c3bac546a

Subscribe to this mod's changes

type-design-analyzer is an agent published in the GitHub repository ronaknnathani/relay (3 stars, last pushed 8d ago), licensed MIT. It adds 71 tokens to every session and 986 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 86% identical to type-design-analyzer, differing in 50 lines, and is treated as a copy.