Redop API Reference

Redop is the main class for building MCP servers. Use the constructor for server metadata and top-level behavior, then register tools, resources, prompts, hooks, middleware, and plugins.

Constructor

new Redop({
  serverInfo: {
    name: "my-mcp-server",
    title: "My MCP Server",
    version: "0.1.0",
    description: "Does X and Y.",
    websiteUrl: "https://example.com/docs",
    instructions: "Always call search before fetch.",
    icons: [
      {
        src: "https://example.com/icon.svg",
        mimeType: "image/svg+xml",
      },
    ],
  },
  capabilities: {
    tools: true,
    resources: true,
    prompts: true,
  },
});

Constructor options

Option	Purpose
`serverInfo`	Grouped MCP-facing metadata returned during `initialize`.
`capabilities`	Enable or disable advertised MCP capabilities.

`serverInfo` fields

Field	Purpose
`name`	Machine-readable server name. Defaults to `"redop"`.
`title`	Optional human-readable display name.
`version`	Version returned during `initialize`. Defaults to `"0.1.0"`.
`description`	Short server description for supporting client UIs.
`icons`	Optional icon metadata from the MCP implementation schema.
`websiteUrl`	Optional canonical site or docs URL.
`instructions`	Optional usage guidance returned as top-level `initialize.instructions`.

Icon shape

icons accepts an array of objects with this shape:

{
  src: "https://example.com/icon.svg",
  mimeType: "image/svg+xml",
  sizes: ["any"],
  theme: "light",
}

Notes:

src is required and should usually be an https: URL or data: URI.
mimeType is optional, but common values are image/png, image/jpeg, image/jpg, image/svg+xml, and image/webp.
sizes supports values like ["48x48"], ["48x48", "96x96"], or ["any"] for scalable icons.
theme can be "light" or "dark".
Clients should treat icon URLs and bytes as untrusted input and apply normal fetch/render safety checks.

Deprecated top-level fields

Redop still accepts top-level name, title, version, description, icons, websiteUrl, and instructions, but they are deprecated. Put new docs and new app code under serverInfo.

Main methods

Method	Purpose
`tool(name, def)`	Register an MCP tool.
`resource(uri, def)`	Register a static or template resource.
`prompt(name, def)`	Register an MCP prompt.
`derive(fn)`	Add reusable request context before hooks and handlers run.
`use(plugin)`	Merge another `Redop` instance as a feature module or plugin.
`middleware(fn)`	Register global middleware.
`onTransform(fn)`	Mutate raw params before schema parsing.
`onParse(fn)`	Replace parsed input before before-hooks and middleware.
`onBeforeHandle(fn)`	Observe each tool, resource, or prompt request before middleware and handlers.
`onAfterHandle(fn)`	Observe successful results after local `after` hooks and before the response is written.
`onAfterResponse(fn)`	Observe tool, resource, and prompt executions after the response is written.
`onError(fn)`	Observe thrown errors from middleware or handlers.
`notifyResourceChanged(uri)`	Push `resources/updated` notifications to subscribed clients.
`handler(opts?)`	Return a portable fetch handler for Cloudflare, Vercel, Node, and other runtimes.
`listen()` / `listen(3000)` / `listen(opts)`	Start the HTTP or stdio transport. Bun is required for HTTP `.listen()`.

Introspection

toolNames returns registered tool names
resourceUris returns registered resource URIs
promptNames returns registered prompt names
getTool(name) returns the resolved tool metadata
getResource(uri) returns the resolved resource metadata
getPrompt(name) returns the resolved prompt metadata
serverInfo returns the MCP server identity used during initialize

Composition pattern

Use .use(...) as the main way to compose a larger server. In practice, that usually means:

create one Redop instance per feature folder
register that feature’s tools, resources, prompts, hooks, or middleware there
import those modules into the root server
attach them with .use(...)

​Constructor

​Constructor options

​serverInfo fields

​Icon shape

​Deprecated top-level fields

​Main methods

​Introspection

​Composition pattern

​Related pages