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[Feature]: Allow disabling the built-in browser/preview MCP tools #4150
Description
Activity
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.
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=falseClaude 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.
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
FWIW I added:
{ "permissions": { "deny": ["mcp__t3-code__*"] } }to my
~/.claude/settings.jsonand that seems to work also. The MCP was consuming several 1000 tokens of context.Reacted by Asheropensoucre- locked and limited conversation to collaborators
on Aug 15, 2026
Before submitting
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