[FEATURE]: Filter which tools are loaded from MCP servers (includeTools/excludeTools)

[marcusquinn]

Feature hasn't been suggested before.

• [x] I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Problem

MCP servers often expose many tools, but agents typically need only a subset. Currently, enabling an MCP loads all its tools into the context window, adding significant token overhead.

Example: The chrome-devtools MCP provides 26 tools (~17k tokens). A UI preview agent might only need 4 of them (~1.5k tokens).

Proposed Solution

Add includeTools and/or excludeTools to MCP configuration:

{
  "mcp": {
    "chrome-devtools": {
      "command": "npx",
      "args": ["-y", "chrome-devtools-mcp@latest"],
      "includeTools": ["navigate_page", "take_screenshot", "new_page", "list_pages"]
    }
  }
}

Or with glob patterns:

{
  "mcp": {
    "github": {
      "includeTools": ["create_*", "list_*"],
      "excludeTools": ["*_dangerous_*"]
    }
  }
}

Per-Agent Override

Combined with per-agent MCP enabling, this allows fine-grained control:

{
  "mcp": {
    "chrome-devtools": {
      "enabled": false,
      "includeTools": ["navigate_page", "take_screenshot", "new_page", "list_pages"]
    }
  },
  "agent": {
    "ui-preview": {
      "mcp": {
        "chrome-devtools": { "enabled": true }
      }
    }
  }
}

Prior Art

Amp recently shipped this feature: Lazy-load MCP with Skills

Their implementation uses a companion mcp.json file per skill. The approach proposed here integrates with OpenCode's existing centralized config pattern.

Benefits

• Token savings: Load only needed tools (17k → 1.5k in the chrome-devtools example)
• Reduced confusion: LLM sees only relevant tools
• Backward compatible: No includeTools = all tools (current behavior)

Related Issues

• #7269 - Subagent list filtering (complementary - filters subagents, not MCP tools)
• #6024 - Provider/model-specific MCPs (complementary - when to load MCPs)
• #7362 - Tool descriptions as skills (similar goal, different approach)

Contribution

Happy to submit a PR for this if the approach is acceptable. We're tracking this in aidevops and can implement a workaround in the meantime, but native OpenCode support would be cleaner.