Obsidian local REST API plugin bundles an MCP server so AI clients can connect directly to your vault

The plugin serves an HTTPS REST API on local 127.0.0.1:27124 and also bundles an MCP server at /mcp/; both expose the same core capabilities: CRUD on any vault file, targeted patches to headings, block references, and frontmatter keys, full-text search and JsonLogic structured queries, event-stream subscriptions, and listing and running Obsidian commands and querying tags. All requests require API key auth, and on first run the plugin creates its own name-constrained certificate authority valid only for specified hostnames such as 127.0.0.1 and localhost, preventing impersonation of other sites. Onboarding differs by client: Claude Code natively supports HTTP MCP and needs a single CLI command; Cursor supports Streamable HTTP via an mcp.json entry; Claude Desktop doesn't support remote HTTP MCP and needs an mcp-remote bridge (Node.js required). Several hard security constraints apply: the API refuses reads and writes to the .obsidian config directory (including data.json, which stores the API key), since writing there is equivalent to remote code execution; ten bad credentials from the same origin within a minute trigger 429 rate limiting, while requests with a valid key are unaffected; and writes support If-Match/If-None-Match conditional requests to prevent two clients from overwriting the same note. For developers managing a knowledge base in Obsidian who want AI agents to operate on notes directly, these rules determine whether a safe integration is possible.