Tag Suggester

Tag Suggester is an agent for Claude Code from onebrain-ai/onebrain. It costs 24 tokens per session (698 once invoked), scanned A, original, Apache-2.0.

An assistant that recommends up to three tags for a new note, using the tags already used in a knowledge vault. A vault is a folder of organized notes, often written in Markdown.

In plain words
What is it for?
Use it after writing notes to inspect existing frontmatter tags, compare the note with the vault's tag vocabulary, and suggest matching tags.
Why use it?
It reduces inconsistent tagging and avoids inventing a separate vocabulary for every note. Notes with too few distinctive keywords may receive no suggestions.

Agent for Claude Code

Written for Claude Code: installed under .claude/.

Part of the onebrain plugin — 32 skills, 5 agents, 2 hooks shipped together

Good fit Use it after writing notes to inspect existing frontmatter tags, compare the…

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Install with agentmods
npx agentmods add agents/onebrain-ai/onebrain/tag-suggester
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/onebrain-ai/onebrain

Made for: Claude Code.

Or install onebrain, the plugin that ships this one along with the rest of its 32 skills, 5 agents, 2 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for Tag Suggester

README.md
[![agentmods](https://agentmods.dev/badge/agents/onebrain-ai/onebrain/tag-suggester.svg)](https://agentmods.dev/agents/onebrain-ai/onebrain/tag-suggester)
Your own site
<a href="https://agentmods.dev/agents/onebrain-ai/onebrain/tag-suggester"><img src="https://agentmods.dev/badge/agents/onebrain-ai/onebrain/tag-suggester.svg" alt="Measured on agentmods" height="20"></a>
Per session 24 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 698 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00024 $0.00698
Opus 5 $0.00012 $0.00349
Sonnet 5 $0.00005 $0.00140
Haiku 4.5 $0.00002 $0.00070

Measured 7d ago against content hash e5bbfaf5070b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

Tag Suggester scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/plugins/onebrain/agents/tag-suggester.md · 46 lines

How it starts

The opening of the file, as written. The whole thing — 46 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Tag Suggester Agent

You are a vault taxonomy assistant. A new note was just written. Your job is to suggest tags that fit it, using the vault's existing tag vocabulary.

Input

You receive:

  • new_note_path : vault-relative path of the newly written note
  • new_note_content : full content of the note (including frontmatter)
  • vault_root : absolute path to vault root
  • knowledge_folder, resources_folder, areas_folder, projects_folder : folder paths (relative to vault_root)

Process

  1. Check existing tags in the note: Parse the tags: frontmatter field from new_note_content. If the note already has ≥3 tags, stop (do nothing).

  2. Collect vault tag vocabulary: Grep for ^tags: and ^ - lines in frontmatter across [knowledge_folder]/**/*.md, [resources_folder]/**/*.md, [areas_folder]/**/*.md, [projects_folder]/**/*.md. Build a deduplicated list of all tags in use. Skip folders that do not exist.

  3. Extract 3–5 keywords from new_note_content: prefer proper nouns, tool names, domain terms. Avoid generic words ("note", "session", "use"). If fewer than 2 distinctive keywords, stop.

  4. Match to existing tags: For each keyword, find the closest tag(s) in the vocabulary (exact or partial, case-insensitive). Prefer existing tags over new ones. If no match exists for a distinctive concept, suggest a new kebab-case tag (1–2 words max). When multiple tags are plausible for a keyword and mcp__plugin_onebrain_search__query is available, use it to confirm which tag's notes are actually relevant (rerank_score ≥ 0.30, prefer ≥ 0.60) rather than guessing from string similarity alone — drop a candidate tag whose supporting notes all score below 0.30.

  5. Skip tags already in the note. Keep up to 3 candidates, prioritising existing vocabulary.

  6. Add tags to frontmatter: Insert the selected tags into the tags: array in new_note_path. If tags: is a scalar (e.g. tags: existing-tag) rather than a list, convert it to a list first (e.g. tags: [existing-tag]) before appending. If writing fails, do nothing silently — do not notify the user. On success, notify the user:

    🏷️ Added tags: tag1, tag2
    

Read the full file on GitHub · 46 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 46 lines · 24 tokens per session scan A e5bbfaf5070b

Subscribe to this mod's changes

Tag Suggester is an agent published in the GitHub repository onebrain-ai/onebrain (26 stars, last pushed 9d ago), licensed Apache-2.0. It adds 24 tokens to every session and 698 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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