AI coding tools (MCP)

This page is about MCP in your editor, while you build an app. To let assistants use a deployed app, see Apps for assistants.

tern mcp serves the Model Context Protocol on stdin and stdout, so AI coding tools can work with a Tern app: list its routes and their types, scaffold routes and live components, run code generation, type checks, tests and builds, and read Tern's documentation for the version the app uses.

#Setup

Run it from the app's root, with the CLI version pinned in go.mod:

• Projects from tern new: they include a .mcp.json, which Claude Code and other tools that read it pick up.

• Claude Code: claude mcp add tern -- go tool tern mcp

• Other tools: add a stdio server with the command go and the arguments tool tern mcp. For example, in a tool that uses mcpServers:

  {
  	"mcpServers": {
  		"tern": { "command": "go", "args": ["tool", "tern", "mcp"] }
  	}
  }
  

#Tools

Tool	What it does
project	the Go module, Tern version, routes, live components, tern.json, package scripts and the Tern packages the app imports
routes	every route: URL pattern, directory, kind, files, Load, Actions, LayoutLoad, endpoint methods, layouts
route_types	the generated $types.d.ts for a route, by pattern (/blog/[slug]) or ID
live_components	components with <script lang="go">, with the TypeScript types of their state and Funcs
generate	tern gen, reporting changed files and warnings
check	tern check, returning the errors with file and line
go_vet, go_test	go vet and go test on a package pattern, optionally -run
build	tern build
new_route	creates a route from a SvelteKit-style path, such as /blog/[slug] or /(app)/settings, with a page, a Load, a form action, endpoint methods or a live page; existing files are kept
new_live_component	creates a .svelte file with <script lang="go" live> to start from
new_migration	tern migrate new
ui_add	tern ui add: copies Tern UI components into src/lib/ui to change them
search_docs, read_doc	the guide, live components, deployment, the SvelteKit migration guide and the decision records, embedded in the CLI

The docs are also resources, at tern://docs/guide.md and so on. The server's instructions tell the model Tern's conventions, such as the Go-safe directory names.

#Safety

• Tool hints: tools that change files or run builds are not marked read-only, so clients that ask before running such tools will ask.
• Paths: the scaffolding tools write only under src/ and migrations/, and never overwrite a file.
• No network: the server makes no network requests of its own.