seo-migration-check

seo-migration-check is a skill for Claude Code from lionkiii/claude-seo-skills. It costs 86 tokens per session (1,097 once invoked), scanned A, original, MIT.

A checker for preserving search-engine visibility when moving pages from one website address to another. It examines redirects, canonical URLs, metadata, content, and structured data.

In plain words
What is it for?
Use it to validate one old-and-new URL pair or a file of pairs after a site migration.
Why use it?
It helps find migration problems such as broken redirects, temporary redirects, missing page information, or content that changed unexpectedly.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the claude-seo-skills plugin — 51 skills, 6 agents shipped together

Good fit Use it to validate one old-and-new URL pair or a file of pairs after a site migration.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/lionkiii/claude-seo-skills/seo-migration-check
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 lionkiii/claude-seo-skills --skill seo-migration-check
Clone the repo
git clone --depth 1 https://github.com/lionkiii/claude-seo-skills

Made for: Claude Code.

Or install claude-seo-skills, the plugin that ships this one along with the rest of its 51 skills, 6 agents.

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 seo-migration-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/lionkiii/claude-seo-skills/seo-migration-check/github.svg)](https://agentmods.dev/skills/lionkiii/claude-seo-skills/seo-migration-check)
Your own site
<a href="https://agentmods.dev/skills/lionkiii/claude-seo-skills/seo-migration-check"><img src="https://agentmods.dev/badge/skills/lionkiii/claude-seo-skills/seo-migration-check/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 seo-migration-check

Your own site · 80×15
<a href="https://agentmods.dev/skills/lionkiii/claude-seo-skills/seo-migration-check"><img src="https://agentmods.dev/badge/skills/lionkiii/claude-seo-skills/seo-migration-check.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 86 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,097 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 $0.00086 $0.01097
Opus 5 $0.00043 $0.00549
Sonnet 5 $0.00017 $0.00219
Haiku 4.5 $0.00009 $0.00110

Measured 12d ago against content hash 8f01fc63233c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

seo-migration-check 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 12d 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/seo-migration-check/SKILL.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Site Migration SEO Validator

Validates redirect chains, canonical tags, metadata, and content preservation during site migrations.

Inputs

Either:

  • old and new: Two URLs for a single-page check (e.g., https://old.com/page https://new.com/page)
  • file: Path to CSV/text file with URL pairs, one per line: old_url,new_url

If file provided: Read it and process each line. Skip blank lines and lines starting with #. For large files (>50 URL pairs), process first 50 and note truncation.

Execution

For each URL pair, run checks a-f:

Check a: Redirect Chain Validation

Fetch old URL with WebFetch and follow redirects (track each hop):

  1. Record redirect type: 301 (permanent), 302 (temporary), 307, 308
  2. Count redirect hops
  3. Record final destination URL

Evaluate:

  • Final destination matches expected new URL: PASS — mismatch: FAIL
  • Redirect type is 301: PASS — 302/307: WARN (temporary redirects pass less link equity)
  • Hop count 1: PASS — hop count 2: WARN — hop count >2: FAIL (redirect chain too long)
  • Direct 200 on old URL (no redirect): FAIL (old page still live, not redirected)

Check b: Canonical Consistency

Fetch new URL, extract <link rel="canonical" href="..."> from <head>.

  • Canonical matches new URL exactly: PASS
  • Canonical missing: WARN (Google will infer, but explicit is better)
  • Canonical points to old URL: FAIL (critical — tells Google old is authoritative)
  • Canonical points to third URL: WARN

Check c: Title and Meta Preservation

Compare title and meta description between old URL (before redirect) and new URL. Note: old URL may already redirect, so if old URL is not directly fetchable, skip comparison and note.

If comparable:

  • Title: Extract both. Compare word overlap.
    • 70% word overlap: PASS

    • 40-70% overlap: WARN (may be intentional change)
    • <40% overlap: WARN with note ("significant title change — verify this was intentional")
  • Meta description: Extract both.
    • Present on both: PASS
    • Missing on new URL: WARN
    • Both missing: NOTE

Read the full file on GitHub · 139 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. 12d ago First seen · 139 lines · 86 tokens per session scan A 8f01fc63233c

Subscribe to this mod's changes

seo-migration-check is a skill published in the GitHub repository lionkiii/claude-seo-skills (20 stars, last pushed 3mo ago), licensed MIT. It adds 86 tokens to every session and 1,097 once invoked, about $0.0004 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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