Syncing MCP Servers

Syncing MCP Servers

This skill ensures MCP server configurations stay in sync between VS Code (repo-level) and Copilot CLI (user-level).

Why This Exists

VS Code and Copilot CLI use different config files with different JSON formats for MCP servers. Neither reads the other's config. This skill bridges that gap.

Format Differences

VS Code format (.vscode/mcp.json)

{
  "servers": {
    "playwright": {
      "command": "npx",
      "args": ["@playwright/mcp@latest", "--viewport-size=1024,768"]
    },
    "microsoftdocs": {
      "type": "http",
      "url": "https://learn.microsoft.com/api/mcp"
    }
  }
}

CLI format (~/.copilot/mcp-config.json)

{
  "mcpServers": {
    "playwright": {
      "type": "local",
      "command": "npx",
      "tools": ["*"],
      "args": ["@playwright/mcp@latest", "--viewport-size=1024,768"]
    },
    "microsoftdocs": {
      "type": "http",
      "url": "https://learn.microsoft.com/api/mcp"
    }
  }
}

Key differences:

1. Top-level key: "servers" (VS Code) vs "mcpServers" (CLI)
2. Local servers: CLI requires "type": "local" — VS Code infers it from "command"
3. Tool filtering: CLI supports "tools": ["*"] (or specific tool names) — VS Code uses "tools" differently in its config
4. Comments: VS Code's mcp.json supports JSON with comments (JSONC) — CLI does not

Workflow

Step 1 — Read the source of truth

Read .vscode/mcp.json from the repo. This is the canonical config, maintained by the team and checked into git.

Step 2 — Read the user's CLI config

Read ~/.copilot/mcp-config.json. This may contain servers from other projects — do not overwrite them.

On Windows: $env:USERPROFILE\.copilot\mcp-config.json On macOS/Linux: ~/.copilot/mcp-config.json

The location can be overridden by the user via --config-dir flag or XDG_CONFIG_HOME env var. Check if either is set.

Step 3 — Convert and merge

For each server in .vscode/mcp.json:

1. Local servers (have "command"): Add "type": "local" and "tools": ["*"] for CLI format
2. HTTP servers (have "type": "http"): Copy as-is — format is identical
3. Skip any server that already exists in the CLI config with matching "command" and "args" (or matching "url" for HTTP types)
4. Warn if an existing CLI server has the same name but different config — ask the user whether to overwrite

Step 4 — Write the updated CLI config

Write the merged config back to ~/.copilot/mcp-config.json. Preserve JSON formatting (2-space indent).

Step 5 — Verify

Run copilot --prompt "list available MCP tools" --allow-all-tools -p "run /mcp show and exit" or instruct the user to run /mcp show in their next CLI session to confirm the servers are available.

Important Rules

1. Never delete servers from the CLI config that aren't in the repo's VS Code config — the user may have servers from other projects
2. Always back up the CLI config before writing: copy to mcp-config.json.bak
3. Strip comments when reading VS Code's JSONC file — parse it as JSONC, not strict JSON
4. Preserve user's existing servers — merge, don't replace
5. Report what changed — list servers added, updated, or skipped

Reverse Sync (CLI → VS Code)

If the user added new MCP servers via CLI (/mcp add) that should also be available in VS Code:

1. Read ~/.copilot/mcp-config.json for any servers not in .vscode/mcp.json
2. Convert: remove "type": "local" and "tools" fields (VS Code infers these)
3. Add to .vscode/mcp.json under "servers" key
4. Preserve existing comments in the JSONC file — add new servers at the end of the "servers" block

Future-Proofing

The CLI and VS Code MCP config formats may converge in the future. Before syncing:

1. Check if CLI now reads .vscode/mcp.json — look for a .vscode/mcp.json or .github/copilot/mcp.json entry in CLI docs or copilot help output
2. Check if the top-level key has changed — CLI may adopt "servers" or VS Code may adopt "mcpServers"
3. Check for a unified config path — a .github/mcp.json or similar repo-level config that both platforms read

If any of these converge, update this skill and simplify the sync process.

Reference

• VS Code MCP docs
• CLI MCP docs
• Custom agents config (tools + MCP)
• CLI flag: --additional-mcp-config @<file-path> — loads extra MCP config for one session without modifying ~/.copilot/mcp-config.json