OpenCode: add an MCP tool, then lock it to one agent

The Stack

Tested Against

Prerequisites

• OpenCode installed
• A provider logged in to actually run it

Steps

1. 1

   Add the MCP server, disable it globally, scope it to one agent

   Declare the Context7 remote server, set tools context7* to false globally, and re-enable it only under the docs agent. Local servers work the same with type: local and a command array. CI parses opencode.json and asserts the scoping is exactly this.

   cat > opencode.json <<'JSON'
   {
     "$schema": "https://opencode.ai/config.json",
     "mcp": {
       "context7": { "type": "remote", "url": "https://mcp.context7.com/mcp" }
     },
     "tools": { "context7*": false },
     "agent": {
       "docs": { "mode": "primary", "model": "provider/your-model", "tools": { "context7*": true } }
     }
   }
   JSON
   node -e 'const c=JSON.parse(require("fs").readFileSync("opencode.json","utf8"));const m=c.mcp.context7;const globalOff=c.tools["context7*"]===false;const agentOn=c.agent.docs.tools["context7*"]===true;if(m&&m.type==="remote"&&typeof m.url==="string"&&m.url.length>0&&globalOff&&agentOn){console.log("config OK: context7 remote MCP, disabled globally, re-enabled only for the docs agent")}else{console.log("BAD");process.exit(1)}'

2. 2

   Use the docs agent (the model step, not checked by CI)

   Switch to the docs agent and the Context7 tools are available there only; everywhere else they stay off, saving context. The model using the tool is fenced, so CI never claims it.