MCP docs

What it is

Ext Watch runs an MCP server: a standard way for AI assistants to use outside tools. Once connected, your assistant can look up our Chrome Web Store data while you chat, instead of guessing.

• Read-only. All 15 tools only read. Nothing can change your account or the store.
• Remote. One address, Streamable HTTP. Nothing to install.
• Dated. Every number comes with the day we read it. Missing values say why, never a made-up zero.
• Cards and charts in apps that support MCP Apps, such as Claude. Other apps get the same answer as text.
• Plans. Included with Silver and Gold. Compare plans.

Connect

You sign in to Ext Watch once per app. Pick yours:

{
  "mcpServers": {
    "extwatch": { "url": "https://app.extwatch.com/api/mcp" }
  }
}

claude mcp add --transport http extwatch https://app.extwatch.com/api/mcp

Example prompts

• “Which productivity extensions grew the most this month?”
• “Show daily users and rating for Loom over the last 6 months.”
• “What do users complain about in PDF editor extensions? Quote the reviews.”
• “Give me 3 extension ideas in note-taking with weak competition, with the evidence.”
• “What launched this week that already has users?”
• “How does Grammarly make money?”

Tools

Your assistant chooses the tool and its arguments from your question. You never need to type these. Each tool reads; none writes.

• search_extensionsSearch extensions1 to 3 credits (1 per 10 rows shown)
• get_extensionExtension profile2 credits
• compare_extensionsCompare extensions2 credits
• get_historyHistory chart1 credit
• find_risersTop risers2 credits
• category_statsMarket stats2 credits
• launches_by_monthLaunches per month2 credits
• get_launchesNew launches1 to 3 credits (1 per 10 rows shown)
• list_reviewsReviews breakdown1 credit
• find_competitorsCompetitors1 credit
• get_publisherPublisher portfolio1 to 3 credits (1 per 10 rows shown)
• get_opportunitiesBuild ideas2 credits
• get_monetizationPayment signs1 credit
• get_collectionCollections1 to 3 credits (1 per 10 rows shown)
• get_changesChanges1 credit

{
  "name": "search_extensions",
  "arguments": {
    "query": "pdf",
    "language": "en",
    "users_min": 10000,
    "limit": 25
  }
}

{
  "name": "get_extension",
  "arguments": {
    "name": "Grammarly"
  }
}

{
  "name": "compare_extensions",
  "arguments": {
    "names": ["Grammarly", "LanguageTool", "QuillBot"]
  }
}

{
  "name": "get_history",
  "arguments": {
    "name": "Loom",
    "metric": "rating",
    "days": 90
  }
}

{
  "name": "find_risers",
  "arguments": {
    "category": "productivity",
    "window": "d30"
  }
}

{
  "name": "category_stats",
  "arguments": {
    "slug": "developer-tools"
  }
}

{
  "name": "launches_by_month",
  "arguments": {
    "months": 12,
    "ai": true
  }
}

{
  "name": "get_launches",
  "arguments": {
    "users_min": 1000,
    "sort": "users"
  }
}

{
  "name": "list_reviews",
  "arguments": {
    "name": "Grammarly",
    "stars_max": 2,
    "sort": "newest"
  }
}

{
  "name": "find_competitors",
  "arguments": {
    "name": "Loom"
  }
}

{
  "name": "get_publisher",
  "arguments": {
    "rank_by": "users",
    "limit": 15
  }
}

{
  "name": "get_opportunities",
  "arguments": {
    "tab": "worth"
  }
}

{
  "name": "get_monetization",
  "arguments": {
    "names": ["Grammarly", "Loom", "QuillBot"]
  }
}

{
  "name": "get_collection",
  "arguments": {}
}

{
  "name": "get_changes",
  "arguments": {
    "names": ["Grammarly"],
    "days": 60
  }
}

Limits

AI apps are part of Silver and Gold. These are the limits for each plan today.

• Each tool’s cost is shown above. Most questions use 1 to 3 credits.
• A call that fails or is refused costs nothing.
• Credits refill each month. Daily limits reset at 00:00 UTC.
• Every answer says how many credits it used and how many are left.
• Free and Bronze don’t include AI apps.

Data freshness

• We read the public Chrome Web Store ourselves. Most listings are read again every day.
• Every number in an answer carries the day it was read, and each answer says how fresh its data is.
• History builds up from the day we started tracking a listing. A missing day shows as a gap, not a zero.
• The store rounds large user counts and sometimes re-measures every rating at once. Answers point these out.
• We hold no revenue, sales or install figures, and the tools never estimate them.

Sign-in and access

Sign-in (OAuth)

When you add the address, your app opens an Ext Watch sign-in page. You sign in and press Allow. The app gets read-only access to the tools and nothing else: not your password, not your settings. Sign-in tokens are short-lived and renew on their own.

API keys

For apps that can’t sign in. Make one in Ext Watch under Settings, then AI assistant, then API keys, and send it as the header Authorization: Bearer ew_live_…. Never put a key in the address. Keys count toward the same plan limits.

Disconnect or revoke

• In Ext Watch: Settings, then AI assistant. Under Connected AI apps, press Disconnect (or Disconnect all). Under API keys, press Revoke. The app loses access within a minute.
• In your assistant: remove the Ext Watch connector as well.
• If your plan changes to Free or Bronze, connections stay saved but lookups pause. Nothing is deleted.

For developers

• A request without a valid token gets HTTP 401 with a WWW-Authenticate header that points to the protected resource metadata. Apps use it to find the sign-in server.
• OAuth 2.1 with PKCE (S256), dynamic client registration and rotating refresh tokens.
• Scope mcp:read. Tokens can be revoked at POST https://app.extwatch.com/api/oauth/revoke (RFC 7009).

What we keep

Your assistant sends only the tool name and its arguments. We never receive your chat, your files or anything else in the conversation.

• For each call: the tool, a fingerprint of its arguments (not the arguments), the result status, the rows and credits used, and the time. Kept 30 days.
• For failed requests: the error, the app’s name and browser type. Kept 30 days.
• Each connection: the app’s name, when it connected and when it was last used, until you disconnect it.

More in our privacy policy.

Errors

A limit or a problem comes back as a normal tool answer marked as an error, so your assistant can tell you what happened. The code is in the answer’s structured content.

plan_required

Ext Watch data in AI apps is part of Silver and Gold, with a link to the plans.Move to Silver or Gold, then ask again. Connecting and listing tools work on every plan.

no_credits

You are out of credits for this month, with the day they refill.Wait for the refill day, or move to Gold for more credits.

daily_credit_cap

You have used today’s credit ceiling.It resets at 00:00 UTC.

quota_exceeded

You have reached today’s call limit.It resets at 00:00 UTC.

daily_row_cap

You have reached today’s limit on results.It resets at 00:00 UTC.

monthly_row_cap

You have reached this month’s limit on results, with the reset day.Wait for the day it names.

rate_limited

Too many requests at once, with the seconds to wait.Wait that long. Assistants usually retry on their own.

blocked

Access is paused on this account because of unusual bulk use.Write to support@extwatch.com.

No listing with that name

Nothing in our crawl matches the name.Check the spelling, or use the store id from the listing’s address.

Too large / took too long

The answer would be too big, or the read took too long.Ask for fewer rows or a shorter window.

Arguments could not be read

A name, filter or value is not one the tool accepts.The assistant usually fixes this itself. The tables above list what each tool accepts.

Tool failed (ref …)

Something failed on our side.Try again in a minute. If it keeps failing, send the ref to support@extwatch.com.

HTTP 401

The sign-in has ended or was removed.Your assistant shows Connect again. Sign in once more.

HTTP 400 on a key in the address

Keys never go in the URL.Send the key as an Authorization: Bearer header.

Troubleshooting

Changelog

Help

Questions or a problem not listed here: support or support@extwatch.com. To report a security issue, see Security.