APIWeaver

Overview

APIWeaver is a lightweight, FastMCP server that turns any web API—whether REST, GraphQL, or other HTTP-based service—into a fully‑functional MCP tool at runtime. By feeding the server an API configuration, developers can instantly expose endpoints as callable tools for AI assistants such as Claude. This eliminates the need to write custom wrappers or SDKs, allowing an assistant to query external services with a single, consistent interface.

The core value of APIWeaver lies in its dynamic registration capability. A configuration file or inline definition describes the base URL, authentication scheme, and endpoint paths; the server then automatically generates an MCP tool for each route. The tools support all standard HTTP verbs (GET, POST, PUT, DELETE, PATCH) and accept query parameters, path variables, headers, and request bodies in a flexible manner. Authentication is handled out of the box with bearer tokens, API keys, Basic auth, OAuth2 flows, or custom headers—ensuring secure access to protected resources without additional code.

Key features include automatic JSON parsing of responses with a graceful fallback to plain text, built‑in connection testing before the tool is exposed, and support for multiple transport layers. The default STDIO transport offers low‑latency local communication, while the recommended Streamable HTTP transport provides bidirectional streaming and robust error handling for cloud deployments. A legacy SSE option remains available for older MCP clients that only support server‑sent events.

In practice, APIWeaver shines in scenarios where AI assistants need to interact with third‑party services on the fly. For example, a product recommendation assistant can query a catalog API to fetch real‑time inventory, or a customer support bot can call a ticketing system’s GraphQL endpoint to retrieve and update tickets—all without writing bespoke code. Because each API endpoint becomes a native MCP tool, developers can compose complex workflows by chaining multiple tools together within the assistant’s prompt logic.

By abstracting away HTTP plumbing and exposing web APIs as first‑class tools, APIWeaver streamlines the integration of external data sources into AI workflows. It empowers developers to rapidly prototype, test, and deploy assistants that leverage the full breadth of existing web services with minimal overhead.