Tag: mcp

Claude Code and GitHub Copilot both ship allowedMcpServers and deniedMcpServers, but the matchers behave differently. serverName is a fallback that a single serverCommand entry silently disables, deny is a union while allow is not, and an invalid allowlist locks everything out.

Agent Plugins 1.0 says plugin.json at the root and mcp.json beside it. Claude Code 2.1.x wants .claude-plugin/plugin.json and .mcp.json. Here is what each client actually loads, tested against a real plugin, and the dual-layout directory that satisfies both.

MCP 2026-07-28 mirrors the JSON-RPC method and target name into HTTP headers so a gateway can route, throttle, and audit without parsing the body. Here is a working gateway, plus the header-body agreement rule that will bite you.

A write tool that asks before it writes needs three things the MCP SDK does not give you: an approval bound to the exact diff, a precondition on the file it previewed, and an integrity-protected requestState. Verified end to end on @modelcontextprotocol/server 2.0.0 against protocol revision 2026-07-28, including the argument-swap that gets past a naive confirm.

Mapping 200 internal REST endpoints to 200 MCP tools puts 200 KB of JSON schema in front of every request. The 2026-07-28 spec also made the usual escape hatch illegal: tools/list MUST NOT vary per-connection, so per-session dynamic registration is gone. Here are the three levers that still work, with measured wire sizes and verified code on @modelcontextprotocol/server 2.0.0.

The GitHub, Postgres, and Slack MCP servers from modelcontextprotocol/servers were archived in 2025 and their npm packages are deprecated. They pin SDK 1.0.1, which cannot negotiate past protocol 2024-11-05. Here is the audit script, the current replacement for each, and the two pointers in the archive README that are themselves stale.

GitHub's August 6, 2026 changelog adds allowedMcpServers and deniedMcpServers to copilot/managed-settings.json. URL and argv matchers, deny-wins precedence, and a fail-closed default the older name-based registry never had.

Microsoft.Agents.AI.GitHub.Copilot 1.16.0 shipped on July 30, 2026. The Copilot CLI runtime now sits behind the ordinary AIAgent abstraction, permissions are deny-by-default, and Squad plugs a whole agent team in as one AIAgent.

Agent skills and MCP servers in GitHub Copilot code review went GA on 2026-07-29. Here is where the files live, why skills load from the head branch, and why every MCP tool call in a review is read-only.

Claude Code 2.1.212+ moves any main-conversation MCP tool call still running at two minutes into a background task. Set CLAUDE_CODE_MCP_AUTO_BACKGROUND_MS=0 to stop it, raise the threshold to move the line, or send progress notifications from the server.