Kiln with Google agents

Use Antigravity for a local Google workflow. It can launch Kiln’s existing Node MCP server directly. You do not need a public tunnel or an OAuth server for Kiln. Sign in to Antigravity normally; your agent supplies the model.

Antigravity CLI#

Install and sign in using Google’s installation guide. Install Kiln using the installation guide. For the current tool set from a checkout:

git clone https://github.com/matthew-kissinger/kiln
cd kiln
bun install --frozen-lockfile
bun run build:runtime
node scripts/create-workspace.mjs ../my-assets --harness agy
cd ../my-assets
node agy.mjs --model gemini-3.8-flash-high

Use the supported Bun 1.4.2 and Node 22.23.3 toolchain. A built package avoids the Bun/build steps: run npm exec --offline -- kiln-init ../my-assets --harness agy from its installation directory instead. Check release compatibility before following saved-asset examples with an older package.

Setup creates .agents/mcp_config.json, a local CLI launcher, AGENTS.md, and authoring/refinement/QA skills with their references. The server entry sets KILN_RESULT_DETAIL=lean: Antigravity writes a result over about 4,000 characters to a file the model then reads back, and the lean review results cost it a quarter fewer result characters in the readiness cycle’s paired sessions; a call’s own detail still wins. Start a new conversation in this workspace and accept normal project/tool trust prompts. Try:

Read AGENTS.md and skills/kiln-author-asset/SKILL.md. Use the kiln_workspace MCP server. Check its capabilities, make a blue one-metre cube on the ground, render it, and review the returned image. Report any connection error.

Then describe the asset you want. Ask for a rendered review and save a revision after accepting the result. Run node kiln.mjs view to open the local asset library. Keep the source alongside the GLB for later edits.

Run agy models to check your account’s available models. Do not assume a generic Flash alias pins 3.8. Google documents model selection and local MCP configuration.

Antigravity desktop or IDE#

Create the same workspace with --harness agy, then open that folder as a project in Antigravity. The generated MCP configuration uses Google’s documented local mcpServers structure. In the IDE, open MCP Servers → Manage MCP Servers to check the connection. Antigravity 2.0 exposes installed MCP servers under Settings → Customizations. Refresh if needed and start a fresh conversation.

Select the desired Gemini model beneath the prompt box. Ask the agent to read the workspace’s AGENTS.md and skill files, then run the connection check above. The copied skills are ordinary readable project files; the generated setup does not promise native slash-command registration. Native Antigravity plugins are an optional packaging route, documented by Google.

These desktop steps follow current official documentation. The latest direct Kiln probe verified the CLI, not an Antigravity desktop recording. Confirm actual tool calls, image receipt and local viewer behavior in your desktop version.

Gemini Spark in the browser#

Spark uses a separate remote connection. Google’s setup starts at Connected Apps → Custom apps, where you enter an MCP server URL and complete account linking. Local stdio commands are not a documented browser connection method. Google’s custom-app instructions.

Kiln’s private compatibility experiment reached registration and its OAuth consent page, but Chrome blocked the final submission. Token exchange, tool execution, inline 3D viewing and downloads in Spark remain unverified. A selected Flash model in ordinary Gemini Chat does not establish Spark’s backend version.

Do not use the experiment’s handwritten OAuth server and rotating tunnel setup as installation instructions. A maintained remote deployment needs authentication, isolated asset storage and a reachable viewer/download route. A tunnel supplies connectivity; it does not supply those application features.

Troubleshooting and verification#

• No tools: open the generated project, accept trust, restart the conversation, and check kiln_workspace. A globally configured kiln may use another install.
• Skill absent: ask the agent to read the project skill’s SKILL.md; keep its referenced files adjacent. Native plugin registration is a separate host feature.
• No inline 3D card: MCP image feedback and MCP Apps are separate capabilities. Use node kiln.mjs view for the local interactive viewer.
• Gemini CLI rejected: our September 8 probe of Gemini CLI 0.59.0 with an individual account returned UNSUPPORTED_CLIENT and directed migration to Antigravity. This does not establish that every Gemini CLI authentication method is unavailable. Follow Google’s migration guide.

Direct probe, September 8, 2026: Antigravity CLI 1.1.27 selected gemini-3.8-flash-high, read project guidance, called kiln_workspace capabilities and render tools, and received a six-view PNG. A separate Hub probe using fresh public checkout c85a76b5b71c8f985c1ae1f762c44c5cb2601a61 also completed native capabilities/render and image inspection after normal Google sign-in. The earlier Windows checkout includes unreleased fixes. CPU feedback establishes geometry/base color, not PBR material fidelity. This was a connection check, not a generation-speed benchmark.

First interactive launch#

Finish Antigravity’s initial onboarding, then start a fresh CLI session. Before submitting an asset prompt, open /mcp and wait until kiln_workspace is connected and its tools are listed. A September 8 Hub test succeeded in print mode but its first interactive session did not expose the MCP tools to the agent. Restarting after onboarding and checking the normal MCP manager restored native tool access without changing Kiln’s configuration. The exact initialization cause is not yet proven; this is a tested readiness check, not a claim that every installation requires a restart. Keep setup checks outside a recorded creation prompt.

The corrected Hub session then created a battleship from a short user prompt, reviewed Kiln’s returned images, saved source and GLB, and resumed the same conversation to paint the three turret roofs dark red. The child revision retained its parent; both GLBs passed validation, and the exported bundle matched the saved source and GLB. The geometry binary was unchanged by the material edit. Native MCP calls and the actual local viewer were recorded. This verifies Antigravity CLI 1.1.27 with gemini-3.8-flash-high and public checkout c85a76b5, not desktop operation or the older eight-tool release package. No Antigravity desktop install was found in the Hub’s checked package and launcher locations.