openapi-to-typescript

A converter that reads an OpenAPI 3.0 specification, a machine-readable description of an API, and creates TypeScript interfaces and type guards from it.

In plain words
What is it for?
Use it to generate request and response types, schema interfaces, and checks for API data from an OpenAPI JSON or YAML file.
Why use it?
It removes the need to write API data types by hand and helps keep TypeScript code aligned with the API specification.

Skill for Claude CodeCodex

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 skills/softaworks/agent-toolkit/openapi-to-typescript
Any agent
npx skills add softaworks/agent-toolkit --skill openapi-to-typescript
Clone the repo
git clone --depth 1 https://github.com/softaworks/agent-toolkit

Made for: Claude Code, Codex.

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,943 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 $0.00060 $0.01943
Opus 5 $0.00030 $0.00971
Sonnet 5 $0.00012 $0.00389
Haiku 4.5 $0.00006 $0.00194

Measured 2d ago against content hash a27383fcaea8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

openapi-to-typescript 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.

skills/openapi-to-typescript/SKILL.md · 345 lines

How it starts

The opening of the file, as written. The whole thing — 345 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OpenAPI to TypeScript

Converts OpenAPI 3.0 specifications to TypeScript interfaces and type guards.

Input: OpenAPI file (JSON or YAML) Output: TypeScript file with interfaces and type guards

When to Use

  • "generate types from openapi"
  • "convert openapi to typescript"
  • "create API interfaces"
  • "generate types from spec"

Workflow

  1. Request the OpenAPI file path (if not provided)
  2. Read and validate the file (must be OpenAPI 3.0.x)
  3. Extract schemas from components/schemas
  4. Extract endpoints from paths (request/response types)
  5. Generate TypeScript (interfaces + type guards)
  6. Ask where to save (default: types/api.ts in current directory)
  7. Write the file

OpenAPI Validation

Check before processing:

- Field "openapi" must exist and start with "3.0"
- Field "paths" must exist
- Field "components.schemas" must exist (if there are types)

If invalid, report the error and stop.

Type Mapping

Primitives

OpenAPI TypeScript
string string
number number
integer number
boolean boolean
null null

Format Modifiers

Format TypeScript
uuid string (comment UUID)
date string (comment date)
date-time string (comment ISO)
email string (comment email)
uri string (comment URI)

Complex Types

Object:

// OpenAPI: type: object, properties: {id, name}, required: [id]
interface Example {
  id: string;      // required: no ?
  name?: string;   // optional: with ?
}

Array:

// OpenAPI: type: array, items: {type: string}
type Names = string[];

Enum:

// OpenAPI: type: string, enum: [active, draft]
type Status = "active" | "draft";

oneOf (Union):

// OpenAPI: oneOf: [{$ref: Cat}, {$ref: Dog}]
type Pet = Cat | Dog;

Read the full file on GitHub · 345 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 345 lines · 60 tokens per session scan A a27383fcaea8

Subscribe to this mod's changes

openapi-to-typescript is a skill published in the GitHub repository softaworks/agent-toolkit (2,413 stars, last pushed 6mo ago), licensed MIT. It adds 60 tokens to every session and 1,943 once invoked, about $0.0003 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.