update_frontmatter
Modify or add YAML frontmatter properties in Obsidian notes to organize metadata, update tags, or remove outdated information.
Instructions
Update or add frontmatter (YAML) properties in a note
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes | Path to the note | |
| properties | Yes | Key-value pairs to set in frontmatter. Use null to delete a property. |
Implementation Reference
- src/index.ts:772-798 (handler)The handler function that executes the update_frontmatter tool: reads the note, parses frontmatter, updates properties (deleting if null), serializes new frontmatter, appends body, and writes back to file.
async function handleUpdateFrontmatter(args: { path: string; properties: Record<string, unknown>; }): Promise<string> { const fullPath = resolvePath(args.path); if (!(await fileExists(fullPath))) { throw new Error(`Note not found at ${args.path}`); } const content = await fs.readFile(fullPath, "utf-8"); const { frontmatter, body } = parseFrontmatter(content); const newFrontmatter = { ...(frontmatter || {}), ...args.properties }; // Remove null values for (const [key, value] of Object.entries(newFrontmatter)) { if (value === null) { delete newFrontmatter[key]; } } const newContent = serializeFrontmatter(newFrontmatter) + body; await fs.writeFile(fullPath, newContent, "utf-8"); return `Successfully updated frontmatter in ${args.path}`; } - src/index.ts:303-317 (schema)Input schema defining parameters: path (string) and properties (object of key-value pairs, null to delete).
inputSchema: { type: "object", properties: { path: { type: "string", description: "Path to the note", }, properties: { type: "object", description: "Key-value pairs to set in frontmatter. Use null to delete a property.", }, }, required: ["path", "properties"], }, - src/index.ts:300-318 (registration)Tool registration in the tools array used for listing available tools.
{ name: "update_frontmatter", description: "Update or add frontmatter (YAML) properties in a note", inputSchema: { type: "object", properties: { path: { type: "string", description: "Path to the note", }, properties: { type: "object", description: "Key-value pairs to set in frontmatter. Use null to delete a property.", }, }, required: ["path", "properties"], }, }, - src/index.ts:930-934 (registration)Registration/dispatch in the switch statement for tool calls.
case "update_frontmatter": result = await handleUpdateFrontmatter( args as { path: string; properties: Record<string, unknown> } ); break; - src/index.ts:421-432 (helper)Helper function to serialize a JavaScript object to YAML frontmatter format, used in the handler.
function serializeFrontmatter(obj: Record<string, unknown>): string { const lines: string[] = []; for (const [key, value] of Object.entries(obj)) { if (value === null || value === undefined) continue; if (Array.isArray(value)) { lines.push(`${key}: [${value.join(", ")}]`); } else { lines.push(`${key}: ${value}`); } } return `---\n${lines.join("\n")}\n---\n`; }