Glean MCP Server implementation

[steve-calvert-glean]

Summary

⚠️ This is an uncharacteristically large PR, and is much larger than what I would normally push as a single change. Going forward additions will be small and focused. Don't hate me.

Initial implementation of a Glean MCP server for search and chat. This PR implements the following:

1. MCP server configured with list and call request handlers
2. search and chat tool implementations
3. Full schema validation support
4. Initial unit tests.

See the README.md Rendered

How to test drive

1. Clone the repo: git clone git@github.com:gleanwork/server-glean.git && cd server-glean
2. Install deps and build: pnpm install && pnpm build
3. Check the tests pass: pnpm test
4. Run the MCP inspector: pnpm inspect. Open the localhost URL provided. You'll need to set two environment variables: GLEAN_SUBDOMAIN (I was using scio-prod to test), and GLEAN_API_TOKEN.
5. Click "List tools", click search. Enter a query and pagesize, then click "Run Tool" (you need to scroll the pane down to see the button).
6. Ensure output returns results.

Example:

mcp-server.mov

[steve-calvert-glean]

The repo/server name is a little general (server-glean - or more precisely @gleanwork/server-glean). I was following a convention that I saw from Anthropic for naming servers, but upon further reflection, it doesn't really do a good job conveying semantic meaning. @john-agan-glean also brought this up as a first reaction - not off base at all.

So, we have a few options:

1. @gleanwork/mcp-server-glean - puts MCP front and center
2. @gleanwork/glean-mcp-server - reads more like English

I'm open to either of those, or other suggestions!

[ghost]

reviewed the code and looks good -- only had minor/non-blocking feedback. I haven't tested it yet...

[ghost]

I'm team @gleanwork/glean-mcp-server or @gleanwork/mcp-server on naming

[steve-calvert-glean]

I'm a big +1 on @gleanwork/mcp-server. Renamed to that!