deplens_inspect — package exports, types (.d.ts), README docs/sections, examples, JSDoc, source analysis
deplens_diff — semver diff between two versions (uses CHANGELOG.md when available)
deplens_doctor — package resolution and runtime/type diagnostics
deplens_project_diff — project dependency changes between lockfiles or Git refs
deplens_check — baseline and policy enforcement for dependency upgrades
deplens_versions — latest and recent npm package versions

Built on the modern McpServer / registerTool API of the TypeScript SDK (≥ 1.18) with Zod input validation, structuredContent outputs, and proper tool annotations.

Run

npx --yes @deplens/mcp

If your MCP host requires command + args:

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

Or install once and call the binary:

npm i -g @deplens/mcp

{ "command": "deplens-mcp" }

Or point directly to the local bin:

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

This starts an MCP server over stdio.

Tools

All tools always populate structuredContent in addition to the text channel. Analysis tools are marked non-read-only because remote inspection writes a local cache and explicit runtime inspection executes package entrypoints.

`deplens_inspect`

Inspect an installed (or remotely downloaded) npm package.

Param	Type	Description
`target`	string (required)	Package name or import path (e.g. `react`, `next/server`, `@scope/pkg`)
`subpath`	string	Optional subpath appended to `target`
`filter`	string	Case-insensitive substring filter, or `/regex/`
`kind`	`('function'\|'class'\|'object'\|'constant'\|'interface'\|'type')[]`	Restrict by export kind
`showTypes`	boolean	Parse `.d.ts` and include function signatures, interfaces, classes, types, enums
`includeDocs`	boolean	Include README preview
`listSections`	boolean	List README section headers
`docsSections`	string[]	Extract specific README sections by name (partial match)
`includeExamples`	boolean	Include code from README, `examples/`, and `@example` JSDoc tags
`search`	string	Semantic search over export names (token matching + JSDoc)
`remote`	boolean	Download into local cache instead of resolving from `rootDir`
`remoteVersion`	string	Version to download when `remote=true` (default: `"latest"`)
`runtime`	boolean	Explicitly import/require the package entrypoint. Defaults off
`format`	`'text'\|'json'\|'object'`	Output format for the text channel. `structuredContent` is always populated.
`maxExports`	number (1–10000)	Max exports to include (default: 100)
`maxSymbols`	number (1–5000)	Max canonical symbols in structured output (default: 250)
`maxProps`	number (1–1000)	Max props per object when `depth>0` (default: 10)
`maxExamples`	number (1–100)	Max examples (default: 10)
`depth`	number (0–5)	Object inspection depth (default: 1)
`resolveFrom`	string	Base directory for module resolution. Defaults to `rootDir`.
`rootDir`	string	Working directory (default: `$DEPLENS_ROOT` or `process.cwd()`)
`jsdoc`	`'off'\|'compact'\|'full'`	JSDoc verbosity mode
`jsdocOutput`	`'off'\|'section'\|'inline'\|'only'`	Where to render JSDoc
`jsdocQuery`	object	Fine-grained JSDoc extraction, including `maxParams` and `paramCursor`
`analyzeSource`	boolean	Analyze JS/TS/Python/Java source for implementation details + complexity
`sourceMaxFiles`	number (1–500)	Max source files to analyze (default: 5)
`sourceIncludeBody`	boolean	Include function body snippets
`language`	`'javascript'\|'typescript'\|'python'\|'java'\|'rust'\|'go'`	Force language detection
`detail`	`'compact'\|'full'`	Versioned structured output projection
`cursor`	string	Resume symbol pagination
`conditions`	string[]	Export conditions in priority order
`cacheDir`	string	Override the shared version cache
`timeoutMs`	number	Bound registry/download work

Example call:

{
  "name": "deplens_inspect",
  "arguments": {
    "target": "ai",
    "showTypes": true,
    "filter": "generate",
    "resolveFrom": ".",
    "jsdocOutput": "section",
    "jsdocQuery": {
      "symbols": "generateText",
      "sections": ["summary", "params", "returns"],
      "tags": { "include": ["param", "returns"] },
      "mode": "compact",
      "maxParams": 5
    }
  }
}

`deplens_diff`

Compare two versions of an npm package.

Param	Type	Description
`package`	string (required)	Package name to compare
`from`	string	Source version: a concrete semver, `"installed"` (default), or `"latest"`
`to`	string	Target version: a concrete semver, `"latest"` (default), or `"installed"`
`filter`	string	Filter exports by name (substring or `/regex/`)
`format`	`'text'\|'json'\|'object'`	Output format for the text channel
`includeSource`	boolean	Include source code complexity comparison
`runtime`	boolean	Import package entrypoints while diffing. Defaults off for safer static comparison
`preferCdn`	boolean	Prefer lightweight CDN downloads instead of full npm installs
`offline`	boolean	Use only versions already present in the local DepLens cache
`includeChangelog`	boolean	Parse `CHANGELOG.md` entries (default: `true`)
`verbose`	boolean	Show detailed per-symbol changes
`rootDir`	string	Working directory for resolution of `from="installed"` (default: `$DEPLENS_ROOT` or `cwd()`)
`conditions`	string[]	Export conditions in priority order
`semantic`	boolean	TypeScript assignability validation (default: true)
`maxChanges`	number	Changes per page
`cursor`	string	Resume change pagination

Project tools

deplens_project_diff accepts from, to, rootDir, lockfile, analyze, includeTransitive, detail, maxChangesPerPackage, packageCursors, packageOnly, strictPackageOnly, projectSnapshot, conditions, and timeout/cache controls. from and to can be Git refs, lockfile paths, or working. API enrichment defaults to detail: "compact", retaining package, summary, changes, semantic compatibility, and per-package pagination. The default page size is 10; use packageCursors to continue selected packages, packageOnly to omit unrelated work, and projectSnapshot to reuse fingerprinted compact analysis. Use strictPackageOnly when an unmatched package filter should mark the MCP result as an error. The result exposes detailLevel; use detail: "full" for the rich per-package diff object.

deplens_check accepts a baseline path plus optional config and failOn. It returns a structured policy result and marks the MCP result as an error when policy fails. Format sarif is available for code-scanning integrations.

deplens_doctor mirrors the CLI Doctor report. deplens_versions is read-only and returns a bounded list of published versions.

Example call:

{
  "name": "deplens_diff",
  "arguments": { "package": "zod", "from": "3.22.0", "to": "3.23.0" }
}

Environment

Variable	Effect
`DEPLENS_ROOT`	Default `rootDir` if a tool call omits it.
`DEPLENS_DEBUG`	When set to `"true"`, emits debug logs to stderr (never `stdout`).

Requirements

Node.js ≥ 22

Development

npm run start            # run the MCP server
npm run inspector        # launch the MCP Inspector against this server

Breaking changes in 0.2.0

Tool names: deplens.inspect → deplens_inspect, deplens.diff → deplens_diff. Dots are not allowed by the MCP tool-name grammar; the new snake_case names match the spec and align with the rest of the MCP ecosystem.
Migration: rename calls in your MCP host config. The input/output schemas are unchanged.