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Voiden MCP Client Beta

The Voiden MCP Client plugin lets you connect to an external MCP server — anything reachable over the network, remote or on localhost — and try out what it offers, the same way .void files already test REST and GraphQL requests. Use it to explore, test, and assert on someone else's MCP server, the reverse direction of the Voiden Tool plugin, which serves your own requests as MCP tools.

Phase 1: Streamable-HTTP transport only — a server that only runs as a local, spawned process (stdio) isn't supported yet.

Key Features​

Tools, Resources, and Prompts​

  • Connect to any Streamable-HTTP MCP server, remote or running on localhost.
  • Pick what you want to call by Type — Tool (an action), Resource (a piece of data by URI), or Prompt (a template) — and Voiden auto-discovers the server's real names for a dropdown, instead of you needing to know them upfront.
  • Tool/prompt arguments are authored as JSON (auto-filled from the tool/prompt's own schema when you pick it), with {{...}} placeholders — environment and runtime variables resolve before the call is sent. (Faker tokens don't yet resolve inside these arguments — support is planned.)
  • If the server requires sign-in, an Authorize button walks you through it in your browser — no manual token copying.

Config Import​

  • Paste a Claude Desktop / Cursor / VS Code / Windsurf-style config directly into a .void file — both {"mcpServers": {...}} and VS Code's {"servers": {...}} shape are recognized — and Voiden fills in the URL and headers automatically. Every HTTP-transport server in the config becomes its own Connection block, not just the first.
  • An mcp-remote-wrapped entry (npx -y mcp-remote <url> [--header ...]) unwraps into the real remote URL and headers directly — it's a stdio↔HTTP bridge, not a local server, so nothing gets spawned.

Reuses Existing Request Machinery​

  • The same Auth block every other protocol uses — including inherited auth from a .voiden-inherited.void ancestor file.
  • The same Headers table, with cookie merging.
  • The same Assertions table, applied to the MCP response.
  • The same code viewer every other block uses for rendering the response body — syntax highlighting, search, and selection, with JSON-encoded text content auto-detected and pretty-printed.

No separate auth system or assertion syntax to learn.

Block Ownership​

This plugin owns 3 block types for MCP server connection, operation, and response rendering:

  • mcp-connection ↗
  • mcpoperation — the Type/Tool/Resource/Prompt picker and arguments editor, part of the MCP Connection block
  • mcp-response — response rendering

Request Pipeline​

The plugin registers build and response handlers for the MCP protocol, reusing the same shared request-building utilities (voiden-rest-api's context.helpers.requestUtils) other protocols use for headers, cookies, query/path params, and auth — rather than a separate hand-rolled implementation.

Dependencies​

{
  "core": ">=2.1.0",
  "sdk": "1.0.10"
}