prinfer

Typehints for your AI agent.

Give AI coding assistant the ability to inspect TypeScript's inferred types mimicking the IDE's hover behavior. so they can write cleaner code without redundant type annotations.

Why?

AI agents write TypeScript, but they can't see what the compiler infers. This leads to:

• Unnecessary explicit type annotations everywhere
• Verbose code that fights against TypeScript's design
• Missed opportunities to leverage type inference

prinfer solves this by exposing TypeScript's type inference to your agent via MCP.

Quick Start

npm i -g prinfer

or

bun add -g prinfer

On install, prinfer automatically configures itself for Claude Code. If auto-setup doesn't run (common with global installs), run:

prinfer setup

What Gets Installed

MCP Server (prinfer-mcp)

Your agent gets a hover tool to check what TypeScript infers at any position:

hover(file: "src/utils.ts", line: 75, column: 10)
hover(file: "src/utils.ts", line: 75, column: 10, include_docs: true)

The position-based API matches IDE behavior and returns instantiated generic types at call sites.

Claude Skill (~/.claude/skills/prefer-infer.md)

A coding guideline that encourages your agent to:

• Rely on type inference instead of explicit annotations
• Use prinfer to verify types before adding redundant hints
• Write idiomatic TypeScript

Plus a /hover command for quick lookups.

Manual Setup

If prinfer setup doesn't work, configure manually:

1. Add MCP server using the Claude CLI:

claude mcp add prinfer node /path/to/node_modules/prinfer/dist/mcp.js

2. Create skill file at ~/.claude/skills/prefer-infer.md with content from prefer-infer.md

CLI Usage

prinfer also works as a standalone CLI:

prinfer src/utils.ts:75:10
prinfer src/utils.ts:75:10 --docs
prinfer src/utils.ts:75:10 --project ./tsconfig.json

Output:

(x: number, y: string) => boolean
returns: boolean
name: myFunction
kind: function
docs: Adds two numbers together.

Programmatic API

import { hover } from "prinfer";

const result = hover("./src/utils.ts", 75, 10);
// => { signature: "(x: number, y: string) => boolean", returnType: "boolean", line: 75, column: 10, kind: "function", name: "myFunction" }

// With documentation
const result2 = hover("./src/utils.ts", 75, 10, { include_docs: true });
// => { ..., documentation: "Adds two numbers together." }

// With custom tsconfig
const result3 = hover("./src/utils.ts", 75, 10, { project: "./tsconfig.json" });

Requirements

• Node.js >= 18.0.0
• TypeScript >= 4.7.0 (peer dependency)

License

MIT