Mavis MCP Server

Expose Mavis's coding tools (bash, edit, git, supabase) to Claude Code via MCP. Let Claude reason. Mavis executes.

What is this?

A Model Context Protocol (MCP) server that wraps the same tools Mavis uses internally and exposes them as MCP tools. When connected to Claude Code, you get a workflow like:

┌──────────────────┐
│  Claude Code     │  ← you talk to Claude
│  (reasoning)     │  ← Claude plans, designs, decides
└────────┬─────────┘
         │ MCP protocol (stdio)
         ▼
┌──────────────────┐
│  Mavis MCP       │  ← thin wrapper
│   Server         │
└────────┬─────────┘
         │ spawns subprocesses
         ▼
┌──────────────────┐
│  bash, git,      │  ← actual execution
│  files, supabase │
└──────────────────┘

Claude thinks (planning, architecture, decisions). Mavis MCP does (shell, file edits, git, supabase, tests, screenshots).

This is the same set of tools Mavis uses when running inside MiniMax Code. The only difference is the interface: instead of a chat loop, Mavis's tools are exposed as MCP tools for Claude.

Related MCP server: Claude Code Control MCP

Why?

Mavis has battle-tested tools for:

• Reading/writing/editing files

• Running bash commands

• Git operations

• Supabase queries

• Running vitest

• Reading screenshots

• Grep / glob search

These are the same tools that make Mavis effective for the KOMO OS codebase. Exposing them via MCP means Claude gets the same operational power without re-implementing anything.

Tools exposed

All tools accept an optional cwd to operate on a subdirectory.

Quick start

1. Install + build

cd mavis-mcp-server
npm install
npm run build

2. Configure Claude Code

Add to your Claude Code MCP config (~/.config/claude-code/mcp.json or via the Claude Code UI):

{
  "mcpServers": {
    "mavis": {
      "command": "node",
      "args": ["/absolute/path/to/mavis-mcp-server/dist/cli.js"],
      "env": {
        "MAVIS_WORKSPACE": "/absolute/path/to/your/project"
      }
    }
  }
}

For development (no build step):

{
  "mcpServers": {
    "mavis": {
      "command": "npx",
      "args": ["tsx", "/absolute/path/to/mavis-mcp-server/src/cli.ts"],
      "env": {
        "MAVIS_WORKSPACE": "/absolute/path/to/your/project"
      }
    }
  }
}

3. Restart Claude Code

The MCP server starts when Claude Code launches. Verify with /mcp in Claude Code.

4. Use from Claude Code

Once connected, Claude can call the tools:

You:  Find all HTTP 400 errors in the supabase logs and propose a fix.

Claude: [plans]
        [calls mavis_search, mavis_bash, mavis_read, mavis_edit, mavis_bash, mavis_run_tests, ...]
        [reports results]

The tools return text content (stdout, file content, etc.) and Claude reasons about the next step.

Architecture

Workspace isolation

The MCP server operates within a workspace directory set via MAVIS_WORKSPACE. All tool calls are scoped to that directory (or its subdirectories via cwd).

This means Claude can't accidentally cd / and rm -rf your home directory. The workspace is a sandbox.

If you pass an absolute path that escapes the workspace, the tool returns an error. Try: mavis_read /etc/passwd → "path escapes workspace".

State

Persistent state lives at <workspace>/.mavis/state.json. It tracks:

• Recent files touched (deduped, capped at 50)

• Last 20 command exit codes

• Workspace metadata (created_at, last_used_at)

State is loaded at startup and saved after each tool call. If the file is missing or corrupt, the server starts fresh.

Security

• All bash commands run with the same privileges as the user

• The workspace boundary is a UX safeguard, not a security boundary

• For real sandboxing, run the MCP server in a container/VM

Defense-in-depth per tool

Each tool has its own safety:

• mavis_bash: no command whitelist; rely on workspace + user trust

• mavis_edit: refuses multi-replace unless all_occurrences=true (prevents accidents)

• mavis_supabase: denylist of dangerous subcommands (db push, db reset, db execute)

• mavis_run_tests: respects workspace; no side effects outside

Examples

Example 1: Fix a bug

You: Fix the off-by-one error in calculateTotal() in src/billing.ts.
     Add a regression test and run the suite.

Claude:
  1. mavis_read src/billing.ts
  2. mavis_search pattern="calculateTotal" glob="*.ts" cwd=src
  3. mavis_read tests/billing.test.ts
  4. mavis_edit old_text="i <= arr.length" new_text="i < arr.length"
  5. mavis_write tests/billing-total.test.ts
  6. mavis_run_tests pattern="tests/billing-total.test.ts"
  7. mavis_bash command="git add -A && git commit -m 'fix: off-by-one in calculateTotal'"

Example 2: Investigate a Supabase error

You: Why are we getting 400s when creating deals?

Claude:
  1. mavis_search pattern="400|invalid" cwd=supabase/functions/komo-deal-engine
  2. mavis_read supabase/functions/komo-deal-engine/_handler.ts
  3. mavis_supabase args=["db", "query", "--linked", "SELECT ... FROM ops_deals WHERE ..."]
  4. mavis_edit old_text="..." new_text="..." (fix)
  5. mavis_run_tests pattern="tests/wire/sprint28"

Example 3: Commit a feature

You: Commit the changes from sprint 29 with a clean message.

Claude:
  1. mavis_git args=["status"]
  2. mavis_git args=["diff", "--stat"]
  3. mavis_git args=["log", "-3", "--oneline"]  (for message style)
  4. mavis_git args=["add", "."]
  5. mavis_git args=["commit", "-m", "feat(sprint-29): ..."]  (Claude writes the message)
  6. mavis_git args=["push", "origin", "main"]

Development

Project structure

mavis-mcp-server/
├── src/
│   ├── cli.ts          # Entry point: parses args, loads workspace, starts server
│   ├── server.ts       # MCP server: registers tools, dispatches calls
│   ├── workspace.ts    # Workspace isolation (sandbox root)
│   ├── state.ts        # Persistent per-workspace state
│   └── tools/
│       ├── index.ts    # Tool registry (re-exports individual tools)
│       ├── types.ts    # ToolDef + ToolContext interfaces
│       ├── bash.ts
│       ├── read.ts
│       ├── write.ts
│       ├── edit.ts
│       ├── search.ts
│       ├── git.ts
│       ├── supabase.ts
│       ├── run_tests.ts
│       └── state.ts
├── tests/              # Vitest tests
├── package.json
├── tsconfig.json
├── vitest.config.ts
└── README.md

Run tests

npm test

Watch mode

npm run test:watch

Build

npm run build

Dev mode (no build)

npm run dev

Status

DONE — initial sprint:

• Project setup (package.json, tsconfig, vitest)

• MCP server skeleton (stdio + tool registration)

• 9 tools implemented

• State management (.mavis/state.json)

• 60 tests (workspace, state, 9 tools, server integration)

• README with Claude Code config + examples

Roadmap

• Streaming responses for long-running tools (bash, run_tests)

• Tool result caching (avoid re-running the same query)

• More tools: mavis_image_read (vision), mavis_lsp (type info)

• Multi-workspace support (one server, many projects)

• OAuth / API key auth for remote Claude Code

• WebSocket transport (instead of stdio only)

Why "Mavis"?

This server's name is Mavis (Model-context-protocol Agent for Versatile Implementation & Support). It's the same agentic loop Mavis uses internally, exposed as MCP.

License

MIT