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thoreinstein

obsidian-mcp

by thoreinstein

obsidian_update_frontmatter

Updates YAML frontmatter in markdown notes safely via single key/value or batch changes, keeping Obsidian metadata consistent.

Instructions

Update YAML frontmatter of a note safely. Supports single key/value or batch updates.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
keyNoFrontmatter key to update (single-key mode)
valueNoNew value for the key (JSON stringified if array/object; single-key mode)
updatesNoJSON object of key/value pairs to set at once (batch mode, alternative to key+value)
file_pathYesRelative path to the note
vault_pathNoOptional vault path override

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

B3.3/5.0
Behavior2/5

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

With no annotations, the description carries the full burden, yet the only behavioral hint is the vague adverb 'safely' – it never explains what safety means, whether existing keys are preserved, permissions needed, or reversibility. For a mutation tool with zero structured behavioral coverage this is a significant gap.

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?

Two short sentences, front-loaded with the core action and followed by the mode support. No filler; every phrase contributes.

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

Completeness3/5

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

For a five-parameter mutation tool with no annotations and no output schema, the description is thin – the meaning of 'safely' and the interaction between single and batch modes are left to inference. It is minimally adequate given the rich schema but does not fully compensate for the missing behavioral detail.

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 description coverage is 100%, so the schema already defines all five parameters. The description's reference to 'single key/value or batch updates' loosely maps to the key/value versus updates parameters but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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

Purpose4/5

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

The description names a specific verb and resource ('Update YAML frontmatter of a note') and clarifies the two operating modes (single key/value vs. batch). It distinguishes the tool's role from siblings like obsidian_replace_in_note or obsidian_insert_at_heading, though it doesn't name or contrast them explicitly.

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

Usage Guidelines3/5

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

Usage is only implied through the mention of 'single key/value or batch updates', which hints at mode selection but doesn't state when to use this over sibling mutation tools or what prerequisites apply. No explicit when-not or alternative routing is provided.

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