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--add-github-mcp-tool issue_write causes no MCP tools to be available #5101
Description
Describe the bug
I'm using Copilot CLI and when running copilot --add-github-mcp-tool issue_write the MCP server in the session will have no available tools:
MCP · GitHub MCP Server
id: github-mcp-server
kind: mcp
name: github-mcp-server
displayName: GitHub MCP Server
scope: Built-in
enabled: ✓ yes (read-only here)
trust: {
"origin": {
"kind": "builtin"
},
"capabilities": {},
"permissions": {}
}
tools (0)
No tools advertised.
...
Affected version
My Copilot CLI version is 1.0.92, and I'm using the online/built-in github-mcp-server.
Through PowerShell on Windows 11.
Steps to reproduce the behavior
- Run
copilot --add-github-mcp-tool issue_write - In the session type
/mcp show github-mcp-server - The output above is displayed (tools (0) - No tools advertised.)
I also noticed, when selecting and copying from the terminal, the text "tools (0) No tools advertised." becomes
tools
Loading tools…
in my clipboard. Not sure if this is an indication of it being stuck trying to load the tools.
Expected vs actual behavior
I would expect the issue_write tool to be available in my session.
Also, I would expect --add-github-mcp-tool to append tools rather than replace all available tools, but perhaps that's by design, although confusing naming. I can confirm copilot --add-github-mcp-tool list_issues "correctly" makes list_issues available as the only tool.
Activity
sean-park-funda commentedon Oct 6, 2026
issue_writeis being filtered out by read-only mode. Two pieces combine here:--add-github-mcp-tool=create_pull_requestleaves the configured endpoint readonly #3052: with--add-github-mcp-tool=create_pull_request, the endpoint stays/mcp/readonly. It has been open since 1.0.39, and a commenter there reports the same behaviour for--add-github-mcp-toolset.pkg/inventory/filters.go#L38,if r.readOnly && !tool.IsReadOnly() { return false }runs before the explicitly-requested-tools check on line 52.issue_writeis annotatedReadOnlyHint: false(pkg/github/issues.go#L2505), so it gets dropped even when you name it.Your "replace instead of append" observation comes from the same code path. If a request names tools but no toolsets, the toolsets are set to empty (
pkg/http/handler.go#L456-L460), so only the tools you named survive. Withlist_issuesthat leaves one tool. Withissue_writeunder read-only it leaves zero, which is what/mcp showreports.What works today: start with
copilot --enable-all-github-mcp-tools. The 0.0.388 changelog entry says this flag "now enables read-write GitHub MCP tools". The 1.0.71 entry adds--add-github-mcp-tool "*", which enables all tools. The cost is that the full GitHub tool list goes into context, not just one tool.Not verified: I don't have Copilot CLI installed, so I haven't checked which endpoint or headers 1.0.92 actually sends. If
issue_writeis still missing after--enable-all-github-mcp-tools, that's worth adding to github/github-mcp-server#3052. The fix belongs in the CLI, which should switch to/mcpwhen an added tool or toolset is a write tool. The server-side ceiling is intentional (handler.go#L335: "Static read-only is an upper bound").Written and posted autonomously by an AI agent at Vibement Inc. (who we are / contact). Based on github-mcp-server at
71ef826(2026-10-03), #3052 and the Copilot CLI changelog, checked on 2026-10-06 (UTC).Xerillio commentedon Oct 12, 2026
@kerobbi I see the issue is completed, but I don't see what the conclusion is.
If
--add-github-mcp-tool <tool>and--add-github-mcp-toolset <toolset>are not meant to be used for write-tools, perhaps that could be added in the documentation andcopilot --helppage?I don't assume the AI-generated comment above is an authoritative (though incomplete) answer?