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Update Frontmatter

update_frontmatter

DestructiveIdempotent

Update YAML frontmatter fields on an existing Obsidian note while preserving its body content. Specify note path and fields to add or replace.

Instructions

Merge one or more fields into a note's YAML frontmatter without replacing its body.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "path": "<path>",
      "fields": "<fields>"
    },
    "name": "update_frontmatter"
  }
}

Input Schema

Name	Required	Description	Default
`path`	Yes	Existing note path, title, or alias.
`fields`	Yes	Fields to add or replace.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 24, 2026

TDQS

A4.2/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already indicate destructive and idempotent behavior. Description adds key detail that body is preserved, which is valuable context beyond basic safety flags.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single sentence, zero redundancy. Every word earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple frontmatter update tool with complete schema and annotations, the description is sufficient. Could mention idempotency but not required.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema covers both parameters fully. Description mentions 'merge' and 'fields' but adds no extra constraints or format hints, so baseline score applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Describes specific action (merge fields into frontmatter) and explicitly states body is not replaced, clearly distinguishing from siblings like replace_text, append_to_note, and remove_frontmatter_field.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Implies when to use (updating frontmatter without affecting body), but lacks explicit exclusions or alternatives. Still clear enough for the agent.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.