Adding MCP Servers Without Opening the Config File: The agy mcp Subcommand
Antigravity CLI 1.1.16, released on August 20, adds an mcp subcommand so you can register and toggle MCP servers without hand-editing JSON. Here is how to add stdio and HTTP servers, isolate a misbehaving one, and script your whole setup so it travels to a new machine.
Find the one broken MCP entry before Antigravity starts, with 40 lines of Node
A single typo in your MCP settings can take every server down with it. Here is a small preflight script that catches the mistakes statically, the real output from a deliberately broken config, and the duplicate-key trap that JSON hides from you.
The MCP Server I Thought I Killed Was Still Holding the Port: 84 Teardown Trials
Closing a session should stop the MCP servers it started. Across 84 trials of four teardown strategies, a process-group SIGTERM left zero orphans — until the child called setsid, at which point it left 100%. Includes a full descendant-sweep implementation.
Startup Dropped to 3ms, and the First Turn Saw Zero Tools
Non-blocking MCP loading cut startup from 2,907ms to 3ms. The wait did not disappear — it moved into the first turn. Here is where it went, measured, plus a readiness gate that waits only for what a turn actually needs.
I Measured Before Writing a Number: MCP Connect and Tool Calls Differed by 486x
Antigravity 2.4.3 lets you set a timeout per MCP server. To find a defensible number I built a stdio server, measured each boundary separately, and found why a single value cannot cover both.
I Copied the Same agent.md Into Another Repo and It Quietly Did a Different Job
CLI 1.1.6 lets you carry agent definitions around as files. I dropped one definition into eight repos, built a preflight that resolves its declared capabilities before the agent runs, and measured it against a naive checker.
Three Tools Named read_file: Catching MCP Name Collisions Before Startup
Bundle enough MCP servers and tool names collide quietly. Here is what a real 5-server, 21-tool setup measured at 43% collision, plus a Python preflight that catches them before startup and assigns deterministic aliases.
When an Unresponsive MCP Server Freezes Your Agent: Separate Timeouts for Connect, List, and Call
Antigravity CLI 1.1.3 closed the case where an unresponsive MCP server stalls an agent forever, by adding timeouts to connect, list-tools, and call-tool. This walks through why the three boundaries fail differently, and builds a defensive wrapper with a circuit breaker and failure-only notifications, backed by working code and a week of overnight runs.
When Your MCP Servers Vanish From the Chat App in Antigravity 2.0
After Antigravity 2.0 split into an IDE and a separate chat-style agent app, an MCP server I had set up in the IDE stopped showing up on the chat side. Here is why the settings scopes are separate, and how to fix it by making a single workspace-level source of truth that both apps read.
Designing MCP Tool Output So It Doesn't Flood Your Agent's Context
When a custom MCP server returns large results in one shot, your Antigravity agent quietly degrades. Field projection, pagination, resource_link, and an output budget keep context from overflowing — shown with concrete TypeScript and measured numbers.
Scope the MCP Tools You Hand an Agent: A Least-Privilege Allowlist Design
As you add MCP servers to Antigravity 2.0, the set of tools every agent can reach quietly grows into an all-you-can-eat buffet. An agent that only needs to read files seeing delete and deploy tools is an accident waiting to happen. This walks through a least-privilege design that scopes tools per agent role, denies at call time, and gates destructive operations behind a second step, with working Python and field notes.
Fixing spawn npx ENOENT When an Antigravity MCP Server Won't Start
Your MCP server config JSON looks correct, but Antigravity logs spawn npx ENOENT and the server stays gray. This is almost always a PATH inheritance problem, not a broken server. Here is how to diagnose and fix it.