Explicitly mentioning the name does not help, but mentioning the MCP server name with the prefix “user-” does work.
Cursor adds that prefix but likely does not include it in its context, so agents are unaware of it and instead expect to find the MCP server without the prefix. This may not be exactly what’s happening, but it appears to be a name mismatch.
I’m running into the same problem and trying to get agent mode working in a dev container. I just updated Cursor today, so it looks like this might be a dev container issue from the latest update.
Your workaround doesn’t work. When is this being fixed?
It’s same for me with supabase.
Running into this too.
It used to work perfectly, but since a few days, enabled MCP’s are not available for the agent (agent telling me the MCP is in error state, while green and enabled in MCP settings).
I have to manually disable and re-enable it and wait a few tens of seconds for it to become (temporarily) available again.
I’m not sure it this will be useful for anyone but in my case (custom MCP server) this issue was fixed by renaming MCP endpoints from mymcp.endpoint to mymcp-endpoint.
This was suggested by Antigravity MCP settings when I was investigating if the issue was with MCP or IDE.
The issue still persists in 2.3.41 (and reverting to 2.3.35 fixed it).
I had the same issue where Cursor reported it doesn’t have direct access to my MCP. I asked if it could see any other MCPs, and it responded it actually does have access to the MCP.
When I tried to use the MCP, it was able to use tool that read, but not tools that write and use arguments. It said CallMcpTool` does not allow it to pass the arguments it needs to pass.
Here is a summary I had it generate:
Title: MCP CallMcpTool cannot pass arguments to Linear tools
Summary
In this workspace, the AI cannot successfully call Linear MCP tools that require parameters (e.g. list_issue_statuses, create_issue) because the CallMcpTool wrapper does not expose an arguments field. As a result, any Linear tool with required arguments fails with input validation errors.
Open a project with the user-Linear MCP server configured (this repo).
From the AI, attempt to call a Linear tool that requires arguments, e.g.:
list_issue_statuses (requires team: string)create_issue (requires title: string, team: string)The AI uses the only available wrapper:
type CallMcpTool = (_: {
server: string,
toolName: string,
}) => any;
arguments object, the tool is invoked with no arguments.MCP error -32602: Input validation error: Invalid arguments for tool create_issue: [
{
"expected": "string",
"code": "invalid_type",
"path": ["title"],
"message": "Invalid input"
},
{
"expected": "string",
"code": "invalid_type",
"path": ["team"],
"message": "Invalid input"
}
]
and similarly for list_issue_statuses:
MCP error -32602: Input validation error: Invalid arguments for tool list_issue_statuses: [
{
"expected": "string",
"code": "invalid_type",
"path": ["team"],
"message": "Invalid input"
}
]
The AI should be able to pass a JSON arguments object through CallMcpTool that matches the MCP tool schemas, for example:
{
"server": "user-Linear",
"toolName": "create_issue",
"arguments": {
"title": "fix(console): Favorite heart rate monitor scan connects to non-favorite devices",
"team": "Software Engineering",
"priority": 2,
"state": "Triage",
"labels": ["Bug"],
"description": "..."
}
}
and:
{
"server": "user-Linear",
"toolName": "list_issue_statuses",
"arguments": {
"team": "Software Engineering"
}
}
The only exposed wrapper is:
type CallMcpTool = (_: {
server: string,
toolName: string,
}) => any;
There is no arguments field, so the AI cannot supply any of the required parameters from the Linear tool schemas:
// create_issue.json (snippet)
{
"name": "create_issue",
"arguments": {
"type": "object",
"properties": {
"title": { "type": "string" },
"team": { "type": "string" },
// ...
},
"required": ["title", "team"]
}
}
// list_issue_statuses.json (snippet)
{
"name": "list_issue_statuses",
"arguments": {
"type": "object",
"properties": {
"team": {
"type": "string",
"description": "The team name or ID"
}
},
"required": ["team"]
}
}
Because CallMcpTool can’t pass arguments, every such call fails with input validation errors from the Linear MCP server.
team argument, even though:
This breaks the /1-create-linear-issue workflow and similar automations.
Update the CallMcpTool tool definition for this workspace to include an arguments field that is passed through verbatim to the MCP tool:
type CallMcpTool = (_: {
server: string;
toolName: string;
arguments?: Record<string, unknown>; // <- needed
}) => any;
So the AI can call, for example:
{
"server": "user-Linear",
"toolName": "create_issue",
"arguments": {
"title": "fix(console): Favorite heart rate monitor scan connects to non-favorite devices",
"team": "Software Engineering",
"priority": 2,
"state": "Triage",
"labels": ["Bug"],
"description": "..."
}
}
Request ID: 0c036ab8-1c8b-42ff-b169-95f71c8241dc
Version: 2.4.9
VSCode Version: 1.105.1
Commit: 4119c25a8bbcda34554ee91403218e9964bfa880
Date: 2026-01-21T04:10:36.693Z
Build Type: Stable
Release Track: Nightly
Electron: 39.2.7
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin arm64 24.1.0
I’m not a very happy user. This bug cost me a lot of time. I wasted several requests trying to resolve the issue. I lost my chat history when I downgraded to resolve the issue.
The quality issues with this app must be improved. I hit blocking issue after blocking issue every time there is an update.
@deanrie , has the root cause of this issue been identified? Is there an ETA for a fix? This is very vexing (I noticed that there was a new release of the Cursor client a day or so ago, but didn’t see this issue mentioned in the changelog, so I assume it’s still present).
Extremely frustrating problem, trying to use the browser tab to troubleshoot. Updated to latest Cursor in hopes of a fix but now browser/globe icon is missing from GUI and still not working??
Version: 2.4.21 (Universal)
VSCode Version: 1.105.1
Commit: dc8361355d709f306d5159635a677a571b277bc0
Date: 2026-01-22T16:57:59.675Z
Build Type: Stable
Release Track: Default
Electron: 39.2.7
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin arm64 23.6.0
Thanks! This has been resolved for me. I’m on nightly Version 2.4.21 now
Same issue here. Please fix. Still experiencing the issue – even on 2.4.21
OK, downgrading to Version: 2.3.41 worked.
But that has now corrupted all my past chats.
Cursor. Please slow down. The regressions are getting unbearable.
We already love you and your tool the way it is.
Rushing to roll out the next feature is not going to make us love you anymore if it means you screwing with the 100 features we’ve already fallen in love with.
And if you don’t want to slow down, at least invest in a good testing stack, pipeline and team to catch regression of existing features before release.
Or have a ‘stable’ and ‘cutting-edge’ release pattern.
Please.
We beg you.
Hey everyone, there’s an update coming soon that should fix this issue. Let me know if the problem still happens.
It’s not just that resources/list is unavailable — the resources/read action is also missing. I’ve attached a screenshot showing the agent explicitly stating that it’s not aware of the resources/read action.
This works correctly in version 2.2. I just want to make sure both issues are being handled.
Thanks.
Any word on whether this is now resolved?
Guys can we have a “stable build”
Like it’s cool if there’s a Russian Roulette “try this version if you dare” but what would really be cool is a “we did quality assurance testing of this version and it doesn’t break everything” kind of version where we can upgrade without wondering if everything is going to break.
Idk how such a destructive change gets pushed that it bricks everyone’s mcp setups but that’s like really bad
Issue still exists for me on the latest version
Version: 2.4.21 (Universal)
VSCode Version: 1.105.1
Commit: dc8361355d709f306d5159635a677a571b277bc0
Date: 2026-01-22T16:57:59.675Z
Build Type: Stable
Release Track: Default
Electron: 39.2.7
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin arm64 25.2.0
Also no MCP support in the CLI
⬡ ListMcpResourcesError: Failed to list MCP resources: MCP error -32601: Method not found
This issue still exists for me and I am on version 2.4.27. Has the fix still not been released yet? This is costing me a lot of time.