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LM Studio MCP Server Setup: mcp.json, Sign-In and Tools

Add a remote LM Studio MCP server in mcp.json: the url entry, browser sign-in since 0.4.10, tool call confirmations, which models use tools and real costs.


Published · Updated · 6 min read

Cover image: X research with a local model

LM Studio MCP setup for a remote server is one mcp.json entry with the server's url, and a browser sign-in since 0.4.10.

This guide adds Weir, so a local model in LM Studio can search X (Twitter) and read posts, threads and profiles. Weir only reads, so it never posts as you. We run Weir.

{
  "mcpServers": {
    "weir": {
      "url": "https://api.weirapp.io/mcp"
    }
  }
}

LM Studio MCP setup: add Weir in four steps

You need LM Studio 0.4.10 or later and a free Weir account.

We read LM Studio's docs and its changelog up to 0.4.26, released 13 October 2026.

  1. Open mcp.jsonIn a chat, open the Program tab in the right sidebar. Click Install, then Edit mcp.json.
  2. Paste the entryAdd weir under mcpServers, as above, and save the file.
  3. Sign inLM Studio opens your browser. Sign in to Weir and approve.
  4. Ask the free question"Use weir: what's my usage?" It calls get_usage, which costs nothing.

Where is LM Studio's mcp.json? LM Studio's MCP launch post puts it at ~/.lmstudio/mcp.json on macOS and Linux. Windows keeps it in %USERPROFILE%\.lmstudio\mcp.json. The post recommends the in-app editor.

Rather click once? LM Studio's docs describe an "Add to LM Studio" link. This one writes the entry above: add Weir to LM Studio.

Which keys does an LM Studio MCP server entry take?

LM Studio's docs show these keys on a remote entry, and Weir needs only url:

Key Weir's value What it does
url https://api.weirapp.io/mcp The server's endpoint
headers Authorization with a key Sends a key instead of signing in
auth leave it out Your own OAuth app's ID and secret
command not used Starts a local server on your machine

Rather use a key? It suits LM Studio versions before 0.4.10. Create one under API keys in your Weir dashboard:

{
  "mcpServers": {
    "weir": {
      "url": "https://api.weirapp.io/mcp",
      "headers": { "Authorization": "Bearer weir_live_your_key" }
    }
  }
}

The key sits in the file as plain text. With a valid key, Weir never asks LM Studio to sign in. See Weir's MCP docs for both routes.

Does LM Studio support OAuth for MCP servers?

Yes: LM Studio 0.4.10, released 9 April 2026, added "OAuth support for MCP servers", its changelog says.

  • Your browser opens. LM Studio sends you to the server's sign-in page, then stores the token.
  • There's no client ID to paste. LM Studio's docs say the auth key is for servers without dynamic client registration. Weir has it, so leave auth out.
  • Update first. Version 0.4.12 fixed sign-in on some Windows setups, and 0.4.14 fixed a token exchange bug.

The link shows under API keys in your Weir dashboard, marked "(MCP)", and revoking it there cuts LM Studio off.

How LM Studio confirms MCP tool calls

LM Studio asks before every tool call, its MCP launch post says, and shows the arguments so you can edit them first.

You can allow a tool once, or always.

"Always" skips the dialog for that tool from then on. Undo it under App Settings, then Tools & Integrations.

Which local models work with LM Studio MCP tools?

Tool use depends on the model you load, and LM Studio's docs sort models into two levels:

  • Native support shows a hammer badge. These models "generally perform better" with tools. The docs' list includes Qwen, Llama 3.1 and 3.2, and Mistral.
  • Default support covers every other model through a built-in prompt. Small models, and models not trained for tools, may write tool calls LM Studio can't read.

Context is the other limit. LM Studio's docs warn that servers built for Claude or ChatGPT can use so many tokens that a local model overflows.

Weir lists 44 tools on a default sign-in. A key made without Reddit access lists no Reddit tools, which keeps the list shorter.

Can LM Studio search X (Twitter)? A worked task

Yes, through Weir, so ask for LM Studio's latest news:

Use weir: what's the latest @lmstudio post on X? Skip replies and reposts.

A tool-calling model should pick search_x. We ran that call through Weir's MCP server on 24 October 2026:

→ search_x {"fromUsers": ["lmstudio"], "query": "-filter:nativeretweets",
            "onlyOriginal": true, "since": "2026-10-01T00:00:00Z", "limit": 1}
← 1 post · 2 credits (1 + 1 × 1) · nextCursor set
  Oct 22  252 likes  14,925 views  "Introducing: Read Aloud"

The post shows a read-aloud feature run by a small local speech model. -filter:nativeretweets drops reposts, which X search returns by default, and onlyOriginal drops replies.

2credits for our 1-post search
11credits for a 10-post search
0credits for get_usage
5,000free Weir credits every month

Weir bills 1 credit per call plus 1 per X post, and failed calls are free. Packs start at $5 for 25,000 credits and never expire, as of October 2026. See every rate on our pricing page.

What we haven't tested

We can't run LM Studio here. This guide comes from LM Studio's docs and changelog, plus a real call through Weir's MCP server.

  • LM Studio's sign-in against Weir. Weir supports the registration LM Studio's docs describe, but we haven't clicked through it.
  • The install link. We built it from LM Studio's format and checked the JSON, not the click.

If it doesn't work

  • Weir doesn't load. Don't nest a second mcpServers. Paste only the weir block inside the existing one.
  • No sign-in appears. Check your version is 0.4.10 or later, or use the key setup.
  • The model never calls a tool. Load a model with the hammer badge, and name Weir in your prompt.
  • A tool returns 402. Your Weir credits ran out, and retrying won't help.

When not to use Weir

  • You want to stay fully offline. Weir is a remote service, so each call goes over the internet.
  • The model has to post or DM. Weir is read-only.
  • Price per post matters most. TwitterAPI.io lists $0.15 per 1,000 tweets as of October 2026, less than our $5 pack.
  • You need a guarantee. Weir isn't licensed by X or affiliated with it, so access can change.

FAQ

Is LM Studio an MCP server?

No. LM Studio is an MCP host: it connects to MCP servers and gives their tools to your local model. Weir is the server in this guide.

Which MCP servers work with LM Studio?

Local servers that run on your machine, and remote ones over HTTP. LM Studio's docs feature Hugging Face, Linear, Notion, Atlassian and Sentry, and say any server that uses OAuth or standard HTTP can connect.

Can LM Studio post to X through Weir?

No. Weir only reads public X data, so nothing can post, like or follow through it.

Sources

All checked on 24 October 2026:

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