Loopback MCP Server

Loopback MCP server is a locally run integration for AI assistants that speak the Model Context Protocol. Feedback bus for coding agents: pin feedback on any web app, an agent fixes it, the pin turns green.

What you get

Loopback is the interactive feedback layer between real product usage and your coding agents: one script tag makes the app you're running locally commentable (Vercel-toolbar-style toolbar, element-anchored pins; deployed public sites go via the /ingest rails instead — see surface compatibility), every pin auto-captures the functional context — failing requests with response bodies, console trail, the route journey that led there, LLM run metadata, typed repro steps — and lands in one project-tagged queue that Claude Code, Codex, and Gemini CLI all work over MCP.

• One instance, all projects. — Every item is tagged with a project slug in
• One queue, all agents. — MCP is the interface, so Claude Code, Codex, and
• A pin is an anchor, not a scope. — Pin a "broken" contact form and the

What the assistant can call

Once Loopback is connected, these are the calls the assistant has available:

• loopback_submit_feedback — File an item: project, type ui\
• loopback_list_feedback — Filter (project/route/status/type/severity/source/assignee) + paginate (total/has_more/next_offset); severity-then-newest
• loopback_get_feedback — Full item: all context + linked change + comment trail
• loopback_update_feedback — Correct an item after filing: title, body, severity, type, project, or route — re-rank a severity, fix a mis-guessed type, move it to the right
• loopback_claim_feedback — Atomic claim; a conflict names the holder; force to take over; open/triaged → in_progress
• loopback_update_status — open → triaged → in_progress → fixed → verified \
• loopback_add_comment — Root-cause notes, questions, reasoning trail
• loopback_link_change — Merge repo/branch/commit/pr_url/diff_summary onto the item
• loopback_resolve_feedback — Close as verified (confirmed for real) or wontfix
• loopback_get_stats — project × status counts

Setting it up

The server ships on npm as loopback-mcp-server, so your MCP client can launch it on demand — there is no separate build step. Add the server block to your client's configuration, restart it, and the tools register themselves.

Configuration and credentials

You will need 2 environment variables: LOOPBACK_HOST, LOOPBACK_TOKEN. The server will not start without them, which is usually why the tools fail to appear on a first run. Keep credentials in your client's env block or a secrets manager rather than in a file you might commit.

Choosing this one

Plenty of developer tooling servers cover similar ground. The differences that matter in practice are scope of access and how much setup stands between you and a working tool call. Loopback's toolset — loopback_submit_feedback, loopback_list_feedback, loopback_get_feedback and 7 more — is a fair guide to whether it matches your workflow. It is maintained by joshidikshant; worth a glance at recent repository activity before you build anything load-bearing on it.

We check each listing at SyncDev against the project's documentation before it goes live — if something here drifts out of date, it is a bug worth reporting.

Before you rely on it

• It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
• With 10 tools registered it takes up a noticeable share of the context window; turn it off in projects that never touch Loopback.
• Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
• MCP clients confirm each tool call by default. Leave that on until you have watched what the loopback mcp server does with a few real requests.