Three coordinated mcp-use releases published on 9 August at 15:41Z describe a developer-workflow change rather than a new general MCP standard. mcp-use 2.1.0, @mcp-use/cli 4.1.0 and @mcp-use/inspector 20.1.0 connect server authoring, inspection and remote development around an experimental Skills-over-MCP path.
A coordinated developer release
CLI 4.1.0 adds experimental server-authoring support for automatic skills/ discovery, explicit disable and directory configuration. The release notes also mention SEP-2640 resource methods, development reloads and build-time embedding. Its bundled authenticated WebSocket tunnel is available through the development command and is described as supporting bounded HTTP, streaming, MCP JSON-RPC and public WebSocket forwarding.
What Inspector and the tunnel add
Inspector 20.1.0 adds typed Skills-over-MCP client operations, a capability-gated file explorer with integrity verification, and removable progressive skill context in Inspector chat. The notes also describe improved discovery, omission of invalid skills from fresh development snapshots and restrictive-by-default widget CSPs. Together, the releases cover the loop from source directory to client-visible behavior.
That convenience has a clear boundary. An authenticated tunnel is still a public-forwarding workflow. Skill provenance, directory permissions, embedded content, capability gates, CSP policy and the data sent through the tunnel need their own review.
Experimental means disposable
Release notes show that the listed features shipped in these versions. They do not establish adoption, stable APIs, measured latency, a completed security review, production readiness or compatibility with every MCP client. This is also not the Agent Plugins package-format story: mcp-use describes authoring, debugging and development transport, not a universal client contract.
A focused pilot
- Install the three pinned versions in a disposable project.
- Create synthetic skills and test discovery, disable, custom directories, resource calls, reloads and build embedding.
- Exercise Inspector typed operations, progressive context, file-integrity checks and restrictive widget behavior.
- Run the tunnel with non-sensitive data and record the URL, authentication path, forwarded messages and logs.
- Confirm that private files and production credentials never cross the forwarder.
Watch for API stabilization, independent security review, latency and failure data, and reports from clients outside the maintainer stack.
Sources: mcp-use 2.1.0, CLI 4.1.0 and Inspector 20.1.0.