Validate Claude Code Setup

Validate Claude Code Setup

Overview

Claude Code settings degrade over time as models evolve, context windows change, and community best practices shift. This skill provides a structured audit and research process to keep ~/.claude/settings.json optimized.

Core principle: Validate every setting against current docs + community consensus before changing. Don't guess — research first, then apply.

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Step 1 — Read Current State

cat ~/.claude/settings.json

Extract the values for these four critical settings:

| Setting | Key | Location | |---|---|---| | Model | ANTHROPIC_MODEL | env block | | Autocompact threshold | CLAUDE_AUTOCOMPACT_PCT_OVERRIDE | env block | | Context window | Model ID suffix (e.g. sonnet[1m]) | env.ANTHROPIC_MODEL | | Effort level | effortLevel | top-level |

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Step 2 — Research Latest Recommendations

Use WebSearch to validate each setting. Always search for current year.

2a. Model context window

Search: "claude sonnet [current model version] context window size 2026" and "claude opus [version] context window"

Decision matrix (as of early 2026):

| Model | Context Window | 1M suffix needed? | |---|---|---| | sonnet (no suffix) | 200K | No | | sonnet[1m] | 1M | Yes (degrades at >400K) | | opus (no suffix) | 200K | No | | opus[1m] | 1M | Yes (good up to ~800K) |

Verdict for daily coding:

• Sonnet → stay at 200K (retrieval collapses at 1M)
• Opus → 1M viable only for massive codebase sessions (76% retrieval at 1M vs 93% at 256K)

2b. Autocompact threshold

Search: "CLAUDE_AUTOCOMPACT_PCT_OVERRIDE best value 2026 context rot"

What the variable does:

• LOWERS the autocompact trigger below the system default (~83-90%)
• Values above ~83 are silently clamped (Math.min bug — search GitHub issues to verify if fixed)
• Setting too low (e.g. 60) → compacts too often, loses useful context
• Setting too high → context rot (model degrades from overloaded window)

Sweet spot as of early 2026: 75

| Value | Effect | |---|---| | 60 | Too early — excessive compaction | | 75 | Sweet spot — avoids rot without over-compacting | | 80 | Acceptable, slightly more context rot risk | | 83+ | At/above clamp limit — effectively same as default |

2c. Effort level

Search: "Claude Code effortLevel best default 2026"

Available values: low, medium, high (persisted); max (Opus only, session-only)

| Value | Thinking | Best for | |---|---|---| | low | Minimal | Batch, boilerplate, renaming | | medium | Selective | Daily dev — official Anthropic default | | high | Almost always | Complex arch, hard debugging | | max | Always deepest | Persistent bugs, critical decisions |

Default recommendation: "medium" — Anthropic changed Opus default from high to medium in 2026; Sonnet docs explicitly recommend medium.

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Step 3 — Apply Validated Settings

After research, update only settings that are out of sync with current best practices.

Optimal baseline config (validate against research before applying):

{
  "env": {
    "CLAUDE_AUTOCOMPACT_PCT_OVERRIDE": "75",
    "ANTHROPIC_MODEL": "sonnet"
  },
  "effortLevel": "medium"
}

To temporarily override per-session:

• Context: /model opus or ANTHROPIC_MODEL=opus[1m] before starting
• Effort: type ultrathink in prompt or /effort high in session

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Step 4 — Verify After Applying

After editing settings.json, restart Claude Code and confirm:

1. Status line shows correct model
2. Compaction doesn't trigger prematurely in a normal session
3. Response quality feels appropriate for effort level

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What to Re-Research When Things Feel Off

| Symptom | What to search | |---|---| | Compacting every 10 turns | CLAUDE_AUTOCOMPACT_PCT_OVERRIDE clamp bug fix + current CC version | | Slow responses / high latency | Claude Code 1M context latency [year] | | Model ignoring middle of files | Claude lost in the middle [model version] [year] | | Shallow reasoning on complex tasks | Claude Code effortLevel high vs max [year] | | Cost exploding | Claude Code token usage by effortLevel [year] |

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Common Mistakes

| Mistake | Fix | |---|---| | Setting autocompact to 60 to "prevent context loss" | That makes it compact MORE. Raise to 75. | | Adding [1m] suffix to Sonnet | Retrieval collapses at 400K. Remove suffix. | | Setting effortLevel: "max" as default | max is Opus-only and session-only. Silently ignored on Sonnet. | | Not researching before changing | Best practices shift every 1-3 months as models update. Always search first. |

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: sennaBruno
• Source: sennaBruno/claude-skills
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.