Model Context Protocol (MCP)

What it means

MCP is an open protocol for connecting an assistant to a remote server that exposes tools. The server publishes tool names and their inputs and outputs; the assistant discovers them and calls the ones it needs. In OneLifeVibe's setup, the MCP server is a remote endpoint over Streamable HTTP.

The protocol separates discovery from execution. Discovery tells the client what is available. Execution sends a specific tool call with arguments and returns a result or an error. That split is useful when you want a connector to expose a stable set of operations to many clients.

How it works

A client starts with initialize to agree on a protocol version, then calls ping to check that the endpoint is responsive. tools/list returns the available tools. tools/call invokes one tool with arguments and returns its result. Notifications are accepted with HTTP 202.

OneLifeVibe supports protocol versions 2025-03-26 through 2026-07-28. It does not use sessions, so do not send an Mcp-Session-Id header, and it does not accept batches. resources/list answers with an empty list.

When a call fails, read the HTTP status first, then the error returned for that call. A transport or sign-in problem is different from a tool-level error, and the fix is different too.

How OneLifeVibe uses it

OneLifeVibe runs two MCP servers. The account connector at https://onelifevibe.com/mcp requires the person's OneLifeVibe sign-in. Use it when a tool needs to read or act on that person's account.

The free connector at https://onelifevibe.com/mcp/free needs no sign-in and is read-only. Use it for read-only discovery or when you do not have an account sign-in.

Both endpoints implement initialize, ping, tools/list and tools/call. resources/list returns an empty list, and notifications are accepted with 202. Both use protocol versions 2025-03-26 through 2026-07-28, with no sessions and no batches.

Common mistakes

The most common mistake is treating the free connector as writable. It is read-only, so a tool that changes account state belongs on the account connector with a valid OneLifeVibe sign-in.

Another is sending an Mcp-Session-Id header or wrapping several requests in a batch. OneLifeVibe does not use sessions and does not accept batches, so those requests will not behave as expected.

Developers also expect resources/list to return a catalog. On OneLifeVibe it returns an empty list. Do not build a discovery flow that depends on resource entries.