REST is a general HTTP contract that any client can call; MCP is a model-facing protocol that lets LLMs call tools through a declarative schema without provider-specific glue.
MCP vs REST API
Tool-calling protocol vs endpoint protocol.
REST is a general HTTP contract that any client can call; MCP is a model-facing protocol that lets LLMs call tools through a declarative schema without provider-specific glue.
REST is generic: endpoints, verbs, JSON in and out. Developers write the client, handle pagination, and parse responses. Nothing in REST is specific to language models — which is also its limitation when the caller is an LLM.
MCP was designed for the model as the caller. An MCP server declares its tools with names, descriptions and JSON schemas. Any MCP host (Claude Code, Cursor, Zed, AGNT itself) can connect and the model sees the tools natively. AGNT exposes both — MCP at /mcp/sse for LLM clients, REST for everything else.
| Axis | MCP | REST API |
|---|---|---|
| Primary caller | LLM | Any HTTP client |
| Discovery | tools/list over SSE | OpenAPI (optional) |
| Invocation | tools/call | HTTP verb + URL |
| Schema | JSON Schema per tool | OpenAPI or none |
| Transport | stdio / SSE | HTTP |
| Ecosystem | Claude, Cursor, Zed, AGNT | Universal |
Use MCP when
- Your caller is an LLM-powered agent.
- You want zero-glue portability across MCP hosts.
- You want tool descriptions that influence routing directly.
Use REST when
- Your caller is traditional software.
- You need the widest possible client reach.
- You're integrating with non-LLM systems.
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FAQ
MCP vs REST API FAQ.
Common questions about choosing between MCP and REST API.
REST is a general HTTP contract that any client can call; MCP is a model-facing protocol that lets LLMs call tools through a declarative schema without provider-specific glue.
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