DepLens

Dependency/API oracle for Node.js and TypeScript. DepLens inspects what is actually installed: runtime exports, type signatures, and JSDoc pulled from .d.ts files, without relying on the internet.

Use it to reduce API hallucination, verify exports, and quickly answer “does this symbol exist in my project?”

Why DepLens

• Local truth: inspects the packages you have installed.
• Runtime + types: shows runtime exports and parsed type signatures.
• JSDoc aware: summaries, params/returns, and tag filters.
• Workspace friendly: --resolve-from for monorepos.
• Fast: Node-first with optional Bun acceleration.

Packages

• @deplens/core — programmatic API
• @deplens/cli — CLI (deplens)
• @deplens/mcp — MCP server (deplens-mcp)

Install

npm i -D @deplens/cli
# or
npx deplens --help

Quickstart

deplens ai --types --filter generate --resolve-from .

Example output (truncated):

🔍 Target: ai (Type Analysis)
🧭 Resolution:
   ResolveFrom: /path/to/project
   Entrypoint: /path/to/node_modules/ai/dist/index.mjs
📄 Package Info:
   Name: ai
   Version: 5.0.97
🔑 Exports Encontrados (100 total):
  📘 Functions (54):
     generateText, generateObject, generateImage, ...
🔬 Type Definitions Analysis:
  📘 Function Type Signatures:
     generateText(options: object): Promise<GenerateTextResult<...>>

CLI Usage

deplens <package-or-import-path> [filter] [options]

Common flags

--types                 Include type signatures (.d.ts)
--filter <text>         Substring filter
--search <query>        Lightweight semantic search (token + JSDoc)
--kind <k1,k2>          function,class,object,constant
--depth <0-5>           Object inspection depth
--resolve-from <dir>    Resolution base directory
--remote                Download package to cache and inspect it
--remote-version <v>    Version for remote download (default: latest)
--docs                  Include README preview
--list-sections         List README section names (for targeted extraction)
--docs-sections <csv>   Extract specific README sections by name
--examples              Include README/examples/@example snippets
--format text|json      Output format
--max-exports <n>       Max exports in output (default: 100)
--max-props <n>         Max props per object (default: 10)
--max-examples <n>      Max examples returned (default: 10)

JSDoc flags

--jsdoc off|compact|full
--jsdoc-output off|section|inline|only
--jsdoc-symbol <name|glob|/re/>
--jsdoc-sections summary,params,returns,tags
--jsdoc-tags t1,t2
--jsdoc-tags-exclude t1,t2
--jsdoc-truncate none|sentence|word
--jsdoc-max-len <N>

Examples

Inspect local package (types + search):

deplens zod --types --search validate --filter parse

Inspect remotely (no install) as JSON:

deplens zod --remote --remote-version latest --format json --filter parse

List README sections and extract specific ones:

deplens zod --docs --list-sections
# then

deplens zod --docs-sections "Getting Started,Usage" --format json

MCP

DepLens ships an MCP server over stdio (@deplens/mcp) so agents can call deplens.inspect and receive structured output.

Run

npx @deplens/mcp

If your MCP host expects a command + args, use one of:

{ "command": "npx", "args": ["--yes", "@deplens/mcp"] }

{ "command": "npm", "args": ["exec", "--", "@deplens/mcp"] }

If your environment has issues with npx/npm exec, install once and call the binary directly:

npm i -g @deplens/mcp

{ "command": "deplens-mcp" }

Or point directly to the local bin if installed in a project:

{
  "command": "node",
  "args": ["./node_modules/@deplens/mcp/bin/deplens-mcp.js"]
}

Note: npm @deplens/mcp is not a valid npm invocation and will print “Unknown command”.

Configure (Claude Desktop / MCP hosts)

Most MCP hosts expect a JSON config with a server command.

Example config snippet:

{
  "mcpServers": {
    "deplens": {
      "command": "npx",
      "args": ["--yes", "@deplens/mcp"],
      "env": {
        "DEPLENS_ROOT": "."
      }
    }
  }
}

Tools

deplens.inspect

Recommended for agents: use format: "json" to avoid parsing human text.

Example tool call payload:

{
  "target": "next/server",
  "showTypes": true,
  "filter": "NextResponse",
  "resolveFrom": ".",
  "format": "json",
  "docsSections": ["Usage", "API"],
  "includeExamples": true
}

The JSON response includes a resolution block to explain where DepLens resolved the module from:

{
  "package": "next",
  "version": "14.2.0",
  "resolution": {
    "target": "next/server",
    "resolveFrom": ".",
    "resolveCwd": "C:\\path\\to\\project",
    "resolved": "C:\\path\\to\\project\\node_modules\\next\\server.js",
    "entrypointPath": "C:\\path\\to\\project\\node_modules\\next\\server.js",
    "entrypointExists": true
  }
}

deplens.diff

Compare two versions of a package. Useful for upgrade planning and identifying breaking changes.

{
  "package": "zod",
  "from": "3.22.0",
  "to": "latest"
}

Programmatic API

import { runInspect } from "@deplens/core";

const output = await runInspect({
  target: "ai",
  showTypes: true,
  filter: "generate",
  resolveFrom: process.cwd(),
});

console.log(output);

Requirements

• Node.js >= 18
• Bun is optional (used if available for extra speed)

License

MIT