# CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
## Project Overview
MCP server that wraps the MCP Inspector CLI, enabling LLM agents to programmatically inspect, debug, and develop other MCP servers. Supports stdio (local commands) and SSE/HTTP (remote URLs) transports.
## Commands
```bash
npm run build # Compile TypeScript to dist/
npm run dev # Watch mode with tsx
npm run check # Type check + lint
npm run lint # oxlint only
npm start # Run built server (node dist/index.js)
```
Test with MCP Inspector:
```bash
npx @modelcontextprotocol/inspector --cli --method tools/list node dist/index.js
```
## Architecture
```
src/index.ts # Entry point - creates McpServer with StdioServerTransport
src/tools/inspector.ts # Tool registration using server.registerTool()
src/services/inspector-cli.ts # CLI wrapper - spawns Inspector CLI process
src/utils/result.ts # Command execution with ResultAsync (neverthrow)
src/types.ts # Type definitions and error kinds
```
**Data Flow**: Tool call → `tools/inspector.ts` handler → `inspector-cli.ts` service → spawns `node @modelcontextprotocol/inspector/cli/build/cli.js` → parses JSON output
**Key Pattern**: For stdio commands like `"node server.js"`, the target string must be split into separate CLI arguments. URLs are passed as-is. See `splitCommand()` in `inspector-cli.ts`.
## Error Handling
Uses `neverthrow` Result types throughout. Never throw exceptions in business logic:
- `ResultAsync<T, InspectorError>` for async operations
- `Result<T, InspectorError>` for sync operations
- Error kinds: `SPAWN_FAILED`, `EXECUTION_FAILED`, `PARSE_FAILED`, `TIMEOUT`, `INVALID_RESPONSE`, `CONNECTION_FAILED`
## Tools Exposed
Six tools for inspecting target MCP servers:
- `mcpdev_inspector_list_tools` / `mcpdev_inspector_call_tool`
- `mcpdev_inspector_list_resources` / `mcpdev_inspector_read_resource`
- `mcpdev_inspector_list_prompts` / `mcpdev_inspector_get_prompt`
All accept `target` (command or URL), `transport` (stdio/sse/http), and `timeout_ms`.
