Obsidian Brain Eval

Measure whether your Obsidian RAG actually works. Generate a gold-set from your vault, score any retrieval backend on Recall@10, and get a PASS or BELOW TARGET grade against a 0.85 default threshold.

When to use this skill

Trigger this skill whenever the user wants to:

1. Test their vault's RAG. "test my obsidian rag", "is my second brain answering well", "does my vault chat work", "rag over my vault test".
2. Measure retrieval quality. "obsidian retrieval quality", "score my obsidian retrieval", "recall at 10 my vault", "obsidian search quality".
3. Benchmark a retrieval system. "obsidian rag benchmark", "compare BM25 vs hybrid in my vault", "evaluate Smart Connections", "Obsidian Copilot eval", "vault retrieval test".
4. Generate a gold-set. "make a gold-set for my vault", "create eval questions from my notes", "gold set obsidian".
5. Establish a CI gate. Run score --backend ... in CI to block retrieval regressions.
6. Decide what to improve next. When Recall@10 < 0.85, the misses tell you where the retrieval layer fails (paraphrase, rare vocab, chunking).

What it does

• `generate` — Sample N representative notes from your vault, ask GPT-4.1 to write ONE natural question per note that the note answers, and write a JSONL gold-set. Each record pins the source note plus any notes it strongly links via frontmatter (entities, topics, related). Costs roughly $1-2 of OpenAI for 40 questions. Idempotent: skips notes already in the gold-set unless --force.
• `score` — Run each gold question through a pluggable retrieval backend and check whether a known-relevant note appears in the top-k. Reports Recall@k, hit/miss per question, and a rank distribution. No GPT cost.

How to run

After installation (see ## Install below):

# Step 1 (optional): generate a 40-question gold-set with GPT-4.1.
# Skip this and use the shipped sample if you don't want to spend GPT.
export OPENAI_API_KEY=...
obsidian-brain-eval generate --vault ~/Documents/MyVault --out gold.jsonl --n 40

# Step 2: score with the zero-infra BM25 backend.
obsidian-brain-eval score --vault ~/Documents/MyVault --gold gold.jsonl --backend naive

# Or score with the LanceDB hybrid backend, against a table you already populated.
obsidian-brain-eval score --vault ~/Documents/MyVault --gold gold.jsonl \
    --backend lancedb --db ~/Documents/MyVault/.lancedb

# CI gate: exit 1 if Recall@10 < 0.85.
obsidian-brain-eval score --vault ~/Documents/MyVault --gold gold.jsonl \
    --backend naive --quiet --json-out result.json

# Try it instantly on the shipped 10-note demo vault.
obsidian-brain-eval score --vault examples/demo-vault \
    --gold examples/sample-gold-set.jsonl --backend naive

Default exit codes:

• 0: score met or exceeded the target (default 0.85)
• 1: score below target
• 2: vault or gold-set missing/unreadable

How to read the output

================================================================
  RECALL@10 - obsidian-brain-eval
================================================================
  questions   40
  hits        37
  Recall@10   0.9250   (target >= 0.85)
  status      PASS
----------------------------------------------------------------
  MISSES
    x  Where do I find notes that compare cloud providers?
       want: vault/concepts/cloud-comparison.md
----------------------------------------------------------------
  HITS (first-relevant rank distribution)
    rank  1: 24
    rank  2: 8
    rank  3: 3
    rank  5: 1
    rank  7: 1
================================================================

Read it in three passes:

1. The headline. Recall@10 + PASS/BELOW TARGET. Done if PASS.
2. The misses. Each miss is a concrete repair: either the gold-set question is too vague, or your retrieval is missing a real signal. Walk these.
3. The rank distribution. Hits clustered at rank 1-2 = retrieval is sharp. Hits drifting to ranks 5-10 = retrieval is finding the right thing but ranking it poorly. The fix is reranking, not more candidates.

Install

Claude Code

pip install "obsidian-brain-eval[naive]"
mkdir -p ~/.claude/skills
git clone https://github.com/build-with-dhiraj/obsidian-brain-eval ~/.claude/skills/obsidian-brain-eval

Then ask Claude Code: "test my obsidian rag at ~/Documents/MyVault using the shipped gold set", or "generate a 40-question gold-set for ~/Documents/MyVault and score it with the naive backend".

Cursor

pip install "obsidian-brain-eval[naive]"
mkdir -p ~/.cursor/skills
git clone https://github.com/build-with-dhiraj/obsidian-brain-eval ~/.cursor/skills/obsidian-brain-eval

Gemini CLI

pip install "obsidian-brain-eval[naive]"
mkdir -p ~/.gemini/skills
git clone https://github.com/build-with-dhiraj/obsidian-brain-eval ~/.gemini/skills/obsidian-brain-eval

Codex CLI

pip install "obsidian-brain-eval[naive]"
mkdir -p ~/.codex/skills
git clone https://github.com/build-with-dhiraj/obsidian-brain-eval ~/.codex/skills/obsidian-brain-eval

Pluggable backends

Two backends ship by default. Both implement the same topk(question, k) -> list[str] protocol so you can drop in your own (see obsidian_brain_eval.backends for the protocol definition).

Custom backends are a 10-line class:

from obsidian_brain_eval.eval import score, load_gold

class MyBackend:
    def __init__(self, vault):
        # Index whatever you want.
        ...

    def topk(self, question: str, k: int) -> list[str]:
        # Return the top-k vault paths, in the canonical 'vaultname/folder/file.md' shape.
        ...

result = score(load_gold("gold.jsonl"), MyBackend("/path/to/vault"), k=10)

What it does NOT do

• It does not modify your vault. Read-only by design.
• It does not run an LLM for the score step. The default target is the pure retrieval-layer Recall@10.
• It does not require an Obsidian plugin install. Pure CLI.
• It does not require Obsidian to be installed at all. Works on any markdown directory with wikilinks.
• It does not measure answer quality. That is a different problem (LLM-as-judge, harness like ragas, etc.). This skill isolates the retrieval gate so when an answer is bad you can tell whether the right note was even retrieved.

Related

• The 30-50 question methodology, gold-set sizing rationale, and pass-threshold defence: docs/RUBRIC.md
• Comparison vs Smart Connections / Obsidian Copilot / vault chat / LangChain eval pipelines / obsidian-graph-auditor: docs/COMPARISON.md
• Companion skill that measures graph topology (orphan rate, modularity, top-hub force-star): obsidian-graph-auditor