MCP Inspector Online — Read mcp.json and Tool Schemas
Inspect Model Context Protocol configs and tools/list payloads in the browser. See stdio commands, HTTP servers, env keys, and JSON Schema inputs for each tool.
See what an MCP server will actually start.
An MCP config is a small JSON file with a large effect: it decides which process or URL your agent can call. Spoold's MCP Inspector shows each server, the command line, and the tool input schema without starting anything.
Two documents, two questions
mcp.json answers which server will run. A tools/list payload answers which functions that server exposes. Cursor and Claude Desktop both use an mcpServers map. A stdio server has command and args. A remote server has url. Environment variables sit on env.
What to check before you restart the client
- The command is on your PATH, or the args point at a real package such as
npx -y. - Paths in args are absolute when the client's working directory is not your project.
- Required tool fields match what you tell the model to send. Optional fields are marked in the inspector.
- Env values are hidden until you ask to see them. Do not share a config that still has a live token.
Workflow
- Copy the config or the tools list.
- Paste it into the inspector, or load the Config and Tools list samples.
- Read the server card or pick a tool chip.
- If a schema is useful as types, send the input schema through JSON → Types.
Inspect an MCP config
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