--- title: "Type Design Analyzer: review, role & definition · Undominated.ai" canonical: https://undominated.ai/agents/anthropic-type-design-analyzer/ description: "Reviews domain types by identifying their invariants, checking where those invariants are enforced, and weighing safer designs against complexity and compatibility." --- # Type Design Analyzer: review, role & definition · Undominated.ai > Reviews domain types by identifying their invariants, checking where those invariants are enforced, and weighing safer designs against complexity and compatibility. [← Explore all agents](/agents/) TESTING AND REVIEW / anthropics # Type Design Analyzer Reviews domain types by identifying their invariants, checking where those invariants are enforced, and weighing safer designs against complexity and compatibility. Use this definition ↓Original source ↗ SOURCE REVIEW Reviewed 2026-09-21 Evidence 4 linked sources Publisher anthropics Licence Apache-2.0 ↗ Revision c447c3207a42 Read what was—and wasn’t—checked ↓ “Use this agent when you need expert analysis of type design in your codebase. Specifically use it (1) when introducing a new type to ensure” anthropics · upstream description ↗ Our analysis follows below. 01 / THE REASONING ## Why this made the selection. - Fixed per-type report: invariants list, four rated axes with justification, Strengths, Concerns, Recommended Improvements. - Anti-pattern list is specific: anemic models, mutable internals, docs-only invariants, missing construction validation, inconsistent mutation guards. ### A good fit for - Reviewing newly introduced domain types on a PR. - A design pass when a type’s illegal states are still representable. ### Weigh up before choosing - Its numerical design rubric is subjective guidance, not a measured quality score or compiler result. - The definition does not specify a tool allowlist or a prohibition on edits; constrain the host to the intended review scope. - Recommendations require the surrounding constructors, mutators and consumers, not just an isolated type declaration. 02 / THE REVIEW RECORD ## What we actually inspected. Source review has boundaries. A clear record is more useful than a “safe” badge. ### Material inspected - plugins/pr-review-toolkit/agents/type-design-analyzer.md (complete frontmatter and body) - plugins/pr-review-toolkit/LICENSE (applicable redistribution terms) - README.md (host and installation guidance) - Host configuration documentation; immutable source and licence hashes ### Our findings - Invariants sought: consistency, state transitions, field relationships, business rules, pre/postconditions. - Principles include making illegal states unrepresentable, constructor validation, and immutability as a simplification. - Improvements must weigh complexity, breaking changes, local skill/conventions, validation performance, and safety vs usability. - When-to-invoke only covers a new type and a PR adding several types—not a whole-codebase audit. - Model `inherit`, color `pink`; no language lock despite access-modifier talk. ### Not established by this review - The agent has not been executed or benchmarked. - Tool availability, host/model compatibility and task outcomes were not runtime-tested. The review applies to the material and revision named here. A newer upstream release can change its behavior. 03 / PUT IT TO WORK ## Use the role in your project. Upstream setup instructions ↗ - Download the original type-design-analyzer.md together with its LICENSE and attribution; inspect its instructions, model choice and tools. - For project use, place the definition in .claude/agents/type-design-analyzer.md; the documented personal scope is ~/.claude/agents/. - Ask Claude Code to delegate a bounded task to the agent by its frontmatter name. Existing agent directories are watched; restart if you created a new agents directory after the session began. - Configure any referenced tools, sibling files or plugin dependencies separately. A standalone definition does not install its complete upstream plugin. ### Before you start - Type definitions (and constructors/mutators) in the diff or workspace. - A type system where encapsulation/access modifiers exist, or the ratings will be forced. - Human judgment before treating scores as quality facts. ### Compatibility Claude Code subagents ### Host-mediated repository and tool access - Frontmatter: no tools, inherit model. Body: evaluate and suggest; does not forbid applying suggestions. - Numeric ratings are instructions to the model, not enforced gates. ### Cost model Definition can be reused under its stated licence. Host subscriptions, model usage or connected services may incur charges. THE COMPLETE REVIEWED DEFINITION ## Read it before you reuse it. Original source bytes, with attribution. Review the host-specific setup notes above. Copy definition ↗ [Download definition + licence ↗](/resources/agents/anthropic-type-design-analyzer/bundle.zip)[Raw Markdown ↗](/resources/agents/anthropic-type-design-analyzer/definition.md) --- name: type-design-analyzer description: Use this agent when you need expert analysis of type design in your codebase. Specifically use it (1) when introducing a new type to ensure it follows best practices for encapsulation and invariant expression, (2) during pull request creation to review all types being added, and (3) when refactoring existing types to improve their design quality. The agent will provide both qualitative feedback and quantitative ratings on encapsulation, invariant expression, usefulness, and enforcement. See "When to invoke" in the agent body for worked scenarios. model: inherit color: pink --- 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? **Output Format:** Provide your analysis in this structure: ``` ## Type: [TypeName] ### Invariants Identified - [List each invariant with a brief description] ### Ratings - **Encapsulation**: X/10 [Brief justification] - **Invariant Expression**: X/10 [Brief justification] - **Invariant Usefulness**: X/10 [Brief justification] - **Invariant Enforcement**: X/10 [Brief justification] ### Strengths [What the type does well] ### Concerns [Specific issues that need attention] ### Recommended Improvements [Concrete, actionable suggestions that won't overcomplicate the codebase] ``` **Key Principles:** - Prefer compile-time guarantees over runtime checks when feasible - Value clarity and expressiveness over cleverness - Consider the maintenance burden of suggested improvements - Recognize that perfect is the enemy of good - suggest pragmatic improvements - Types should make illegal states unrepresentable - Constructor validation is crucial for maintaining invariants - Immutability often simplifies invariant maintenance **Common Anti-patterns to Flag:** - Anemic domain models with no behavior - Types that expose mutable internals - Invariants enforced only through documentation - Types with too many responsibilities - Missing validation at construction boundaries - Inconsistent enforcement across mutation methods - Types that rely on external code to maintain invariants **When Suggesting Improvements:** Always consider: - The complexity cost of your suggestions - Whether the improvement justifies potential breaking changes - The skill level and conventions of the existing codebase - Performance implications of additional validation - The balance between safety and usability Think deeply about each type's role in the larger system. Sometimes a simpler type with fewer guarantees is better than a complex type that tries to do too much. Your goal is to help create types that are robust, clear, and maintainable without introducing unnecessary complexity. The download contains type-design-analyzer.md . Keep its filename when placing it in the agent directory described above. By **anthropics**. Exact upstream source ↗ · [Licence](/resources/agents/anthropic-type-design-analyzer/LICENSE.txt) · [Attribution](/resources/agents/anthropic-type-design-analyzer/ATTRIBUTION.txt) SHA-256 c1cf67843d3c4fd27ddf6b24aa92521414b16c01610e7f7e87212c7b8681198d Read the applicable licence Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. 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Check upstream before adopting a new version. - type-design-analyzer — complete upstream definition ↗ Checked 2026-09-21 https://github.com/anthropics/claude-plugins-official/blob/c447c3207a425bc4e2a0d068435f64b0477ae981/plugins/pr-review-toolkit/agents/type-design-analyzer.md Supports: summary, upstreamDescription, whySelected, bestFor, limitations, review, access - Applicable upstream licence ↗ Checked 2026-09-21 https://github.com/anthropics/claude-plugins-official/blob/c447c3207a425bc4e2a0d068435f64b0477ae981/plugins/pr-review-toolkit/LICENSE Supports: license, artifact - Repository installation and scope guidance ↗ Checked 2026-09-21 https://github.com/anthropics/claude-plugins-official/blob/c447c3207a425bc4e2a0d068435f64b0477ae981/README.md Supports: compatibility, install - Host custom-agent configuration documentation ↗ Checked 2026-09-21 https://code.claude.com/docs/en/sub-agents.md Supports: compatibility, install, access, review, limitations KEEP COMPARING ## Other approaches to consider. Related by category or shared topics. These are alternatives to inspect, not a measured quality order. [### FastAPI Reviewer ↗ Reviews FastAPI changes for async blocking, dependency wiring, schema exposure and test setup, with file references and explicit unverified risks.](/agents/ecc-fastapi-reviewer/)[### Hypothesis Debugging Investigator ↗ Investigates one assigned bug hypothesis and sends the team lead a cited account of supporting evidence, contradictions and remaining gaps.](/agents/wshobson-team-debugger/)[### Playwright Test Explorer ↗ Explores a working interface through Playwright before generating and running TypeScript tests for its observed user flows.](/agents/github-playwright-tester/) [AI Tools ↗](/tools/)[Skills ↗](/skills/)[Agents ↗](/agents/)[MCP Servers ↗](/mcp-servers/)