This PR add supports to MCP version 2025-06-18 defined
[here](https://modelcontextprotocol.io/specification/2025-06-18).
The main updates includes:
* Retrieving protocol version from header via `MCP-Protocol-Version`.
* Throwing `400 Bad Request` when an invalid version is received.
Allow Toolbox server to automatically update when users modify their
tool configuration file(s), instead of requiring a restart.
This feature is automatically enabled, but can be turned off with the
flag `--disable-reload`.
This feature includes the following:
* Implement initialize lifecycle (including version negotiation)
* Add the v20250326 schema
* Supporting the `DELETE` and `GET` endpoint for MCP.
* Supporting streamable HTTP (without SSE).
* Terminating sessions after timeout (default = 10 minutes from last
active).
* Toolbox do not support batch request. Will response with `Invalid
requests` if batch requests is received.
Currently the `stdio` transport protocol will throw a `ZodError` during
initialization. This is due to Toolbox writing `null` to stdout when it
received a notification. This is not expected hence the `ZodError`
occurs. Per the MCP protocol, notifications do not expect any response.
This fix added a condition to check if the responses is `nil` before
writing to stdout.
Update MCP server to support toolset.
User can now connect to specific toolset's sse via
`/mcp/{toolset_name}/sse` url, or POST to `/mcp/{toolset_name}`. If
toolset_name is not provided, it will list all tools by default.
Fixes#403
