llm-model-selection

llm-model-selection is a skill for Claude Code, Codex from avizmarlon/agent-skills. It costs 51 tokens per session (1,206 once invoked), scanned A, original, MIT.

A method for choosing a large language model, meaning an AI system that generates or analyzes text and code, using relevant benchmarks and real performance data.

In plain words
What is it for?
It compares models for chat, coding, classification, and other uses, considering task results, speed, cost, context length, and instruction following.
Why use it?
It reduces the risk of choosing a model based only on reputation or broad tests that do not match the actual task.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Claude Code.

Good fit It compares models for chat, coding, classification, and other uses, considering task results, speed, cost, context length, and instruction following.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/avizmarlon/agent-skills/llm-model-selection
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 avizmarlon/agent-skills --skill llm-model-selection
Clone the repo
git clone --depth 1 https://github.com/avizmarlon/agent-skills

Made for: Claude Code, Codex.

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 llm-model-selection

README.md
[![agentmods](https://agentmods.dev/badge/skills/avizmarlon/agent-skills/llm-model-selection/github.svg)](https://agentmods.dev/skills/avizmarlon/agent-skills/llm-model-selection)
Your own site
<a href="https://agentmods.dev/skills/avizmarlon/agent-skills/llm-model-selection"><img src="https://agentmods.dev/badge/skills/avizmarlon/agent-skills/llm-model-selection/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 llm-model-selection

Your own site · 80×15
<a href="https://agentmods.dev/skills/avizmarlon/agent-skills/llm-model-selection"><img src="https://agentmods.dev/badge/skills/avizmarlon/agent-skills/llm-model-selection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,206 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 $0.00051 $0.01206
Opus 5 $0.00026 $0.00603
Sonnet 5 $0.00010 $0.00241
Haiku 4.5 $0.00005 $0.00121

Measured 9d ago against content hash 656ac45d78c4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

llm-model-selection 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 9d 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.

skills/llm-model-selection/SKILL.md · 73 lines

How it starts

The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.

LLM Model Selection — Consult Benchmarks Before Choosing

When a task requires you to recommend or select an LLM for a specific use case, follow a systematic process before defaulting to a well-known model name:

1. Check Existing Benchmarks First

If you or your team have already run benchmarks (bake-offs) for similar use cases, that prior data is more valuable than generic leaderboards. Reasons:

  • Context-specific results trump averages. A model that ranks #2 on MMLU may rank #1 on your specific task (code generation, legal analysis, math reasoning).
  • Real-world performance differs from benchmark suites. Generic leaderboards test broad knowledge; your task has specific constraints (latency budget, cost per call, long-context handling, instruction-following precision).
  • You avoid redundant work. If you've already benchmarked "agent reasoning on financial data," reuse that result instead of re-running it on a similar financial-domain task.

If an existing benchmark covers your use case: use the winner as your default choice. Note the selection criteria so you can explain the decision.

2. When to Re-Benchmark

If your use case diverges from existing benchmarks, narrow the test scope and run a fresh benchmark:

  • Scope mismatch: existing benchmark was for "summarization" but your task is "multi-step reasoning with chain-of-thought"
  • Different constraints: existing test was on 4K-token documents; you need 100K-token handling
  • New model release: new frontier models are available since the last benchmark
  • Cost/latency window changed: you now have stricter latency budget or cost ceiling

When re-benchmarking, use existing benchmarks as prior signals — especially for known weaknesses (e.g., "GPT models historically fail at precise JSON output; Claude handles it better"). This lets you design a test that's smaller and faster than the original.

3. Always Validate Availability & Pricing Live

Never trust model names or pricing from memory or old docs. Models are deprecated, renamed, and repriced frequently. Always query the live API or vendor's current listing:

Read the full file on GitHub · 73 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. 9d ago First seen · 73 lines · 51 tokens per session scan A 656ac45d78c4

Subscribe to this mod's changes

llm-model-selection is a skill published in the GitHub repository avizmarlon/agent-skills (2 stars, last pushed 2mo ago), licensed MIT. It adds 51 tokens to every session and 1,206 once invoked, about $0.0003 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 2026-08-31.

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