rag-vs-finetune-decision

rag-vs-finetune-decision is a skill for Claude Code from VandanaAjayDubey111/great-pm. It costs 109 tokens per session (4,222 once invoked), scanned A, original, MIT.

A decision guide for choosing between prompt changes, RAG, and fine-tuning for an AI system. RAG retrieves relevant outside information at answer time, while fine-tuning changes how a model behaves through additional training.

In plain words
What is it for?
Use it to decide how to address missing knowledge, missing behavior or format, cost, and response-time problems in an AI feature.
Why use it?
It helps avoid using fine-tuning when clearer instructions or retrieved information would solve the problem, while weighing cost, speed, and maintenance.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions Codex.

Part of the great-pm plugin — 114 skills, 34 commands, 48 agents, 5 hooks shipped together

Good fit Use it to decide how to address missing knowledge, missing behavior or format, cost, and response-time problems in an AI feature.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vandanaajaydubey111/great-pm/rag-vs-finetune-decision
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.

Any agent
npx skills add VandanaAjayDubey111/great-pm --skill rag-vs-finetune-decision
Clone the repo
git clone --depth 1 https://github.com/VandanaAjayDubey111/great-pm

Made for: Claude Code.

Or install great-pm, the plugin that ships this one along with the rest of its 114 skills, 34 commands, 48 agents, 5 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 rag-vs-finetune-decision

README.md
[![agentmods](https://agentmods.dev/badge/skills/vandanaajaydubey111/great-pm/rag-vs-finetune-decision/github.svg)](https://agentmods.dev/skills/vandanaajaydubey111/great-pm/rag-vs-finetune-decision)
Your own site
<a href="https://agentmods.dev/skills/vandanaajaydubey111/great-pm/rag-vs-finetune-decision"><img src="https://agentmods.dev/badge/skills/vandanaajaydubey111/great-pm/rag-vs-finetune-decision/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for rag-vs-finetune-decision

Your own site · 80×15
<a href="https://agentmods.dev/skills/vandanaajaydubey111/great-pm/rag-vs-finetune-decision"><img src="https://agentmods.dev/badge/skills/vandanaajaydubey111/great-pm/rag-vs-finetune-decision.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 109 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,222 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 $0.00109 $0.04222
Opus 5.5 $0.00044 $0.01689
Sonnet 5.5 $0.00022 $0.00844
Haiku 4.5 $0.00011 $0.00422

Measured 1mo ago against content hash 9d844d7b7fd5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rag-vs-finetune-decision 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 1mo 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.

plugins/great-pm/skills/rag-vs-finetune-decision/SKILL.md · 284 lines

How it starts

The opening of the file, as written. The whole thing — 284 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codex host binding

  • Treat references to Claude slash workflows as the equivalently named Codex skill.
  • Before delegating to any specialist, read the great-pm-runtime skill and the selected packaged role file.
  • Treat "invoke", "assign", "delegate", "spawn", and source Agent-tool instructions as a required Codex spawn_agent call with that role and a bounded assignment.
  • For the spawn tool's task_name or agent_name identifier, replace canonical role-name hyphens with underscores (query-refiner-pm → query_refiner_pm). Keep canonical names unchanged in prompts, filenames, verdict logs, and user-facing output; this is an internal identifier mapping, not a role rename.
  • Store every returned agent identifier. Never call a wait tool until a spawn has returned an identifier, and wait only on identifiers returned by successful spawns.
  • If spawn_agent is unavailable or a spawn fails, report BLOCKED; do not impersonate the specialist or wait on an empty agent set.
  • Resolve bundled paths from the installed GreatPM plugin root.
  • Ignore Claude-only model aliases, colors, turn limits, and tool allowlists.
  • Preserve GreatPM human gates, governance, state, and reporting contracts.

RAG vs Fine-tune Decision — the model-capability ladder

When an AI feature isn't good enough, teams reach for the most expensive, least reversible fix — fine-tuning — far too early. The discipline this skill enforces: climb the capability ladder prompt → RAG → fine-tune only as far as the problem actually requires. Roughly 99% of products never need fine-tuning. The decision is not "which is most powerful" — it is where the missing capability actually lives, and the cheapest rung that closes that specific gap.

The diagnosing question for every gap: does the model lack instructions, knowledge, or behavior?

  • Missing instructions (it can do it, but you asked badly) → prompt engineering.
  • Missing knowledge (it doesn't know your facts, or they go stale) → RAG.
  • Missing behavior / format at scale, or a latency/cost problem from huge repeated prompts → fine-tuning (only after prompt + RAG fail).

Read the full file on GitHub · 284 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. 1mo ago First seen · 284 lines · 109 tokens per session scan A 9d844d7b7fd5

Subscribe to this mod's changes

rag-vs-finetune-decision is a skill published in the GitHub repository VandanaAjayDubey111/great-pm (3 stars, last pushed 1mo ago), licensed MIT. It adds 109 tokens to every session and 4,222 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-09-21.