[Feature]: Allow disabling the built-in browser/preview MCP tools

[kevhardy]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area

apps/server

Problem or use case

t3code automatically adds its browser MCP tools to the provider's session. When users already have a browser workflow configured, such as Playwright or another browser MCP, agents see overlapping tools operating on different browser contexts. This can cause agents to select the wrong tool, inspect the wrong page, or mix browser state. There is currently no supported way to disable T3 Code's browser MCP.

Proposed solution

Add a server-level setting to disable the built-in browser MCP, with the current behavior remaining enabled by default. When disabled, t3code should neither register the MCP server nor inject related browser instructions. A setting could be exposed in the General section of the UI to toggle it off or passed in as a cli flag.

Why this matters

Users should be able to make their configured browser MCP the single authoritative browser workflow. This would reduce tool ambiguity and make agent behavior more predictable.

Smallest useful scope

A cli flag passed that prevents any t3code related MCP injections from being added to new sessions.

Alternatives considered

Telling agents to specifically ignore t3code mcp tools. Still retains the context of those tools.

Risks or tradeoffs

No response

Examples or references

No response

Contribution

• I would be open to helping implement this.

[stanley50z]

Agree. It seems like T3's in app browser is prioritized most of the time, and the workarounds are not elegant. prompting to prioritize the other browser tool don't work very well, and telling agent to ignore T3's tool adds unnecessary context to sessions not in t3code.

[kevhardy]

Current workaround for Codex and Claude by adding these to their Launch arguments under their respective provider options:

Codex Launch arguments:

-c mcp_servers.t3-code.url=http://127.0.0.1:1/mcp -c mcp_servers.t3-code.enabled=false

Claude Launch arguments:

--disallowedTools 'mcp__t3-code__*'

Note: This seems to remove their tools but the browser related developer instructions will still be in their initial prompt.

[Asheropensoucre]

i agree i dont want to use the MCP at all i keep telling the model to stop using it but it keeps running tests with it burning my tokens until this is fixed its makes the app unstable on a pro plan

[bman654]

FWIW I added:

{
  "permissions": {
     "deny": ["mcp__t3-code__*"]
  }
}

to my ~/.claude/settings.json and that seems to work also. The MCP was consuming several 1000 tokens of context.

[TheBit]

I guess this was shipped today to nightly: #7083

[juliusmarminge]

Implemented in #7083. Settings → Integrations → Browser now lets you disable agent browser access, including the injected browser instructions for new sessions. Closing this request as completed.

[gthay]

Should we change it to a project based Setting?
With some projects I have playwright setup and would like to use that and not the t3 MCP, with other smaller projects I don't and would like to use it there. A global disable does not solve that.
What do you guys think?