MCP vs REST API: Token Costs, Latency & AI Agent Integration Comparison

## MCP vs REST API: Architectural Comparison for AI Agents As autonomous coding assistants (Claude Code, Cursor, Windsurf, Codex) become primary interfaces for digital operations, developers must choose how to expose publishing capabilities: traditional REST endpoints or Anthropic's Model Context Protocol (MCP). --- ### Technical Trade-Offs | Metric | Model Context Protocol (MCP) | Standard REST API | | :--- | :--- | :--- | | **Protocol** | JSON-RPC 2.0 via Stdio / SSE / HTTP Stream | HTTP 1.1 / HTTP/2 (JSON over REST) | | **Tool Discovery** | Native runtime schema introspection (`tools/list`) | Requires manual OpenAPI / Swagger ingestion | | **Token Overhead** | Schemas remain in agent context during session | Only active requests consume generation tokens | | **Execution Ergonomics** | Direct natural language function calling | Requires client-side script wrapper or curl invocation | --- ### Token Cost Considerations MCP tools require their JSON schemas to be present in the system prompt context. For large tool suites (30+ tools), this consumes approximately 1,500 to 3,000 prompt tokens per turn. However, the elimination of custom integration glue code and deterministic schema enforcement significantly reduces model hallucination and retry costs.