LM-P-0062026-11-024 min read

MCP connector with Claude vs. Gemini

MotifSpec’s MCP server worked in Claude the first time I added it. Gemini said it had trouble connecting. Once it connected, the same kind of request showed how far the design system bends beyond a portfolio.

MotifSpec has a hosted MCP server at https://mcp.motifspec.com/mcp, so any AI assistant can read the design system’s rules and check its own markup against them. It’s read-only and needs no sign-in. I built and tested it with Claude, where it worked the first time. When I added it to Gemini, it failed.

Adding it to each #

In Claude, the server is a custom connector: paste the address and it’s available in a new chat. In a code project, Claude Code reads it from a small file in the repository:

json .mcp.json

{
  "mcpServers": {
    "motifspec": {
      "type": "http",
      "url": "https://mcp.motifspec.com/mcp"
    }
  }
}

In the Gemini app it’s a custom connected app: choose Customize, then Connectors, then + Custom, and paste the same address. It needed nothing under Additional settings. Google’s help page lists a few conditions on the account: you have to be 18 or over, in the US, signed in with a personal Google Account, and have Keep Activity turned on. Gemini CLI uses a settings file like Claude Code’s, but with one trap: there, url means the older SSE transport, and a Streamable HTTP server like this one needs httpUrl instead.

Where Gemini stopped #

Gemini’s only message was “We had trouble connecting to this server. Contact the server provider for help.” I was the server provider, so I sent the server the kinds of requests a stricter client might, and three of them failed:

What changed in MotifSpec 1.17.1 The same requests, before and after
Request	Before	After
A GET, which some clients send after connecting to open a stream for live updates	Held open until the Lambda timed out after 10 seconds, then an error	Refused at once: the server has no updates to send
A request that accepts only JSON, anything, or doesn’t say	Refused with 406 Not Acceptable	Answered in JSON, as every other request is
A browser’s CORS check before calling from another site	Refused	Allowed: the server is read-only and has no sign-in

None of these stopped Claude. After the fix shipped in MotifSpec 1.17.1, Gemini connected. I can’t say which of the three it needed, because I fixed them together.

The same kind of request, two results #

With both connected, I asked each for something MotifSpec wasn’t designed for: an admin dashboard for a homelab.

A Gemini chat. The prompt reads “using MotifSpec, create a mockup of an admin style dashboard for a homelab management system”, and Gemini shows that it is working, with the status “Verifying content compliance”. — Plate 1The prompt in Gemini, with the connector working.

Gemini built a case study. “Homelab cluster console” has my name as the wordmark, the site’s Work, Writing and About navigation, an “All work” link, a catalogue number (LM-W-009) with a filing date and a role, a numbered plate for the network diagram, and a table of contents. Every part follows the specification, and almost none of them belongs on a dashboard.

A page titled Homelab cluster console under a header reading Liam Marshall, Cluster admin, with Work, Writing and About links. Above the title is an accession label with the number LM-W-009, a filed date, the role Systems architect, a stack of Raspberry Pi 5, Docker, Prometheus and WireGuard, and a Live status. Below are two buttons, a network diagram captioned as Plate 1, a table of contents, a warning about an NVMe temperature, and the start of a node telemetry table. — Plate 2Gemini’s dashboard is a case study: catalogue number, plate and table of contents, because those are the parts the specification has.

Claude came closer to a dashboard: a “Homelab control panel” header with its own navigation, stat tiles, and a card for each node with usage bars. It still borrowed the portfolio’s vocabulary, with an accession-style label for the rack, catalogue numbers for each node, and heading anchors on the sections.

A page titled Overview under a header reading Homelab, Control panel, with Overview, Nodes, Services, Storage and Network links. Below are Run backup now and Add service buttons, a label with the number LAB-01, the date the rack was commissioned, four nodes, the uplink and a Live status, and a warning that a storage pool is 86% full. Four tiles show nodes online, services, storage used and power draw, and four node cards show CPU, memory and disk as bars. — Plate 3Claude’s version reads as a dashboard, but the stat tiles and usage bars aren’t parts MotifSpec defines, and the catalogue numbers come from the portfolio.

Neither result is wrong, given what the assistants had to work with. MotifSpec’s components are the ones a portfolio needs: case studies, posts, cards, figures and tables. There is no stat tile, meter or status list, so one assistant used what was there and the other built what was missing. The specification can hold any site to its rules, but it can only shape the kinds of pages it has components for.

What I’d take from it #

The first request in the table is the one I’d watch for. The MCP spec lets a server without live updates refuse that GET outright, but the library I used kept the request open instead, and nothing in my tests sent one. Claude worked regardless; Gemini didn’t, and its error message couldn’t say why. Testing a server only against the client you built it with tests that client’s patience, not the server. Each request in the table is now a test, so the server is held to the stricter behaviour from here on. The dashboards point to the next release: components for the pages people will actually ask for, so the rules have something to work with beyond a portfolio.

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