Agent Skills

What it checks

The extension fetches /.well-known/agent-skills/index.json, the discovery index defined by agentskills.io (discovery v0.2.0). When that returns a successful, non-empty JSON response, it parses the document and checks that:

• it is valid JSON,
• it has a top-level skills array, and
• every entry in the array has a name and a description.

If the index is not there, the extension also tries two older paths that are not in the spec, /.well-known/agent-skills.json and /.well-known/skills.json, so a site using one is told where the manifest should go rather than being told it has none.

Results

Status	When
Pass	The index is valid and every skill has a name and description
Warn	The index is not valid JSON, has no skills array, or has entries missing a name or description
Warn	No index, but a manifest was found at one of the older, non-standard paths
N/A	No skills manifest was found at any of the paths

How to fix

Publish the index at /.well-known/agent-skills/index.json, with a skills array in which every entry names the skill and says what it does:

{
  "skills": [
    {
      "name": "order-lookup",
      "description": "Look up the status of an order by its order number."
    }
  ]
}

If you already have a manifest at /.well-known/agent-skills.json or /.well-known/skills.json, move it to the path above.

Related: MCP Server Card.

Support by agent and browser

Announced means the vendor’s own docs or announcement say so. Published is the date on the vendor’s own page, where it has one. Checked is the last time our weekly research found that page still saying so.

No agent or browser has announced anything about this yet.

No evidence yet27

• ChatGPT
• Claude
• Gemini
• Perplexity
• Copilot
• Meta AI
• ChatGPT Atlas
• Comet
• Dia
• Gemini in Chrome
• Edge Copilot Mode
• Claude Code
• Cursor
• Codex
• GitHub Copilot
• Windsurf
• CCBot
• Applebot
• Amazonbot
• Bytespider
• Cohere
• Mistral
• DuckAssist
• Chrome
• Edge
• Firefox
• Safari

Names and marks belong to their owners and are used only to identify products. None of these vendors is affiliated with Sitebulb. Spotted something out of date? Send a correction.

Adoption on the top 100 sites

3%

3 of 91 measured sites implement it

Scanned 23 Oct 2026 with the Sitebulb Labs extension, against the Tranco list (tranco-56Z8N). 9 sites couldn’t be measured (bot challenge or timeout) and are left out of the share.

Sites implementing it3

1. #2 cloudflare.com
2. #68 zoom.com (via zoom.us)
3. #106 sentry.io

Overview

1/9

Stalled

No meaningful support, or vendors have said no.

How this rating is worked out1 of 9 points

Factor	Points	Why
Vendor support	0 / 3	0 vendors supporting, 0 partly or planned
Top-100 adoption	1 / 3	3% of measured sites
Spec maturity	0 / 3	Community proposal

8 or more points is Established, 5 to 7 is Gaining traction, 2 to 4 is Speculative and under 2 is Stalled. A feature is also Stalled when more vendors have said no than yes. Read the spec.

Community insights

No community insights for this feature yet.

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