Support file-based MCP server configuration (mcp.json)

[Philipp0205]

Add support for discovering MCP server configurations from mcp.json files, same as in VSCode and GitHub Copilot CLI and probably intelliJ (not tested)

Supported locations (lowest to highest priority):

1. Global: ~/.config/github-copilot/eclipse/mcp.json (Linux/macOS) / %APPDATA%\github-copilot\eclipse\mcp.json (Windows)
2. Project: <project>/.vscode/mcp.json
3. Project: <project>/.github/copilot/mcp.json

Servers from all sources are merged. Manual preference configuration and extension-point contributions retain highest priority.

[jdneo]

Hi @Philipp0205,

Thank you for your contribution. I have some question about this request:

I did not find any official docs that mentioning to identify .github/copilot/mcp.json as a standard/well-known MCP discovery location, could you please paste the reference about this location?

Meanwhile, I find that Copilot CLI uses ~/.copilot/mcp-config.json: https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/add-mcp-servers#editing-the-configuration-file

[Philipp0205]

Hi @jdneo, you are right <project>/.github/copilot/mcp.json does not exist, I mixed something up here :) Regarding the PR (if it is considered), we should make two changes:

1. support mcp.json file at the project root
2. and ~/.copilot/mcp-config.json.

Reference: (https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-command-reference). Also note that in the CLI docs call the project root "workspace" which does not match the definition in the eclipse world.

I also decided to not extend the existing preferences page of the MCP preferences page since it got very busy. Instead I created a new sub page but I am always open for feedback!

[jdneo]

Thank you for the information, I did not find https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-command-reference#mcp-server-trust-levels before. This list is very helpful.

I got a feeling that we can consider support Repository (.github/mcp.json) instead of Workspace (.mcp.json) at first stage.

Because .github/mcp.json is a clear definition, which somehow mitigate the issue that: the project root "workspace" which does not match the definition in the eclipse world

So the support list will be:

1. Repository (.github/mcp.json)
2. User config (~/.copilot/mcp-config.json)

WDYT?

[Philipp0205]

I agree, I would like .github/mcp.json more than the project root since the .github folder is the dedicated place for copilot stuff and we don't need to watch file changes at the project root. On the other hand we would not have complete feature parity with the cli but since I know nobody who stores mcp config at workspace (cli definition) level I am personally fine with that :)

[jdneo]

Cool, let's go ahead with these two. BTW, I will be OOF during May 1 - May 5, please expected a little bit delay for code review. Thanks.

[Philipp0205]

@jdneo great! No worries, I will update the PR once I have time and then it can be reviewed whenever suitable.

[jdneo]

Thank you. I think we can do it progressively, so in the first pr, let's focus on .github/mcp.json and ~/.copilot/mcp-config.json only.