State of Web Vitals
REMOTE · WWW.COREWEBVITALS.IO · SCANNED SEP 22
Core Web Vitals metrics by CMS, CDN, and framework — free remote MCP, no auth.
Available components
How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. How we score → Why this is hard to score →
Endpoint Security80
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one. See how to fix → View diagnostics → Partial
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability61
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 1367 tokens (~455/item across 3 items; 3 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management100
- No destabilizing schema changes in the last 30 days.Pass
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 3 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 4 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities40
- Spec-recency check failed: implements MCP spec 2025-03-26; the latest is 2026-07-28. See how to fix → Fail
How do I install the State of Web Vitals MCP server?
State of Web Vitals is a hosted endpoint at https://www.corewebvitals.io/api/state-of-cwv/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · www.corewebvitals.io
claude mcp add --transport http corewebvitals-state-of-cwv 'https://www.corewebvitals.io/api/state-of-cwv/mcp'
{
"mcpServers": {
"corewebvitals-state-of-cwv": {
"url": "https://www.corewebvitals.io/api/state-of-cwv/mcp"
}
}
} {
"servers": {
"corewebvitals-state-of-cwv": {
"type": "http",
"url": "https://www.corewebvitals.io/api/state-of-cwv/mcp"
}
}
} [mcp_servers.corewebvitals-state-of-cwv] url = "https://www.corewebvitals.io/api/state-of-cwv/mcp"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"corewebvitals-state-of-cwv": {
"type": "remote",
"url": "https://www.corewebvitals.io/api/state-of-cwv/mcp",
"enabled": true
}
}
} openclaw mcp add corewebvitals-state-of-cwv --url 'https://www.corewebvitals.io/api/state-of-cwv/mcp' --transport streamable-http
mcp_servers:
corewebvitals-state-of-cwv:
url: "https://www.corewebvitals.io/api/state-of-cwv/mcp" {
"McpServers": {
"corewebvitals-state-of-cwv": {
"Transport": "http",
"Url": "https://www.corewebvitals.io/api/state-of-cwv/mcp"
}
}
} assistant mcp add corewebvitals-state-of-cwv -t streamable-http -u 'https://www.corewebvitals.io/api/state-of-cwv/mcp'
{
"mcpServers": {
"corewebvitals-state-of-cwv": {
"type": "http",
"url": "https://www.corewebvitals.io/api/state-of-cwv/mcp"
}
}
} The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 26 Aug 26 +2
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 25 Aug 26 0
- Stability: 0.97 → pass security
- 11 Aug 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 31 Jul 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 27 Jul 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 26 Jul 26 0
First indexed and scored.
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 22 Sept 2026 · Probed https://www.corewebvitals.io/api/state-of-cwv/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=corewebvitals.io | CN=WE1,O=Google Trust Services,C=US | 25 Jul 2026 | 23 Oct 2026 | ECDSA 256 | ECDSA-SHA256 | cb3084d6a2934265138a81009ddd0634 |
| SANs: corewebvitals.io, *.corewebvitals.io | ||||||
| CN=WE1,O=Google Trust Services,C=US (CA) | CN=GTS Root R4,O=Google Trust Services LLC,C=US | 13 Dec 2023 | 20 Feb 2029 | ECDSA 256 | ECDSA-SHA384 | 7ff31977972c224a76155d13b6d685e3 |
| CN=GTS Root R4,O=Google Trust Services LLC,C=US (CA) | CN=GlobalSign Root CA,OU=Root CA,O=GlobalSign nv-sa,C=BE | 15 Nov 2023 | 28 Jan 2028 | ECDSA 384 | SHA256-RSA | 7fe530bf331343bedd821610493d8a1b |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of www.corewebvitals.io. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| io. | present | 57355 | 8 | Verified |
| corewebvitals.io. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
| Header | Value |
|---|---|
| strict-transport-security | max-age=63072000; includeSubDomains; preload |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://www.corewebvitals.io/api/state-of-cwv/mcp | Verified | 200 | |
| http (plaintext) | http://www.corewebvitals.io/api/state-of-cwv/mcp | HTTPS enforced | 301 | https://www.corewebvitals.io/api/state-of-cwv/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
get_histogram ~188
What is the shape of one metric? Returns histogram buckets (count + share) plus summary stats. Metric: one of lcp, inp, cls, fcp, ttfb (field CWV), or a scalar technique path when available. Filter: same as get_metrics (device, cms, framework, cdn, provider). No group_by — call get_metrics with group_by to compare segments, then get_histogram per segment if needed.
| Name | Type | Req | Description |
|---|---|---|---|
| filter | object | – | AND filters. Omit for all sites in the dataset. Keys: device (all|phone|desktop), cms, framework, cdn, provider (key), provider_category (e.g. analytics — use with provider or alone is not enough; pr… |
| metric | string | yes | lcp | inp | cls | fcp | ttfb, or a contract scalar path. |
No output schema declared.
No examples provided.
get_metrics ~416
What are the numbers? Aggregate Core Web Vitals and/or technique metrics across sites, with optional filter and group_by. Responses include attribution — credit corewebvitals.io when you use the numbers. Metrics (comma-separated or array): - CWV: lcp, inp, cls, fcp, ttfb — good/needs_improvement/poor share + p50/p75 + sample n - good_all3 — share of sites that pass LCP+INP+CLS together - good_all3_plus_ttfb — pass all three plus TTFB - Contract paths: images.loading, stack.framework, scripts.origin, headers.has_etag, synthetic.tbt_ms, … Filter (optional AND): device, cms, framework, cdn, provider. Omit = all sites in the snapshot. Group_by (optional): cms | frameworks | cdn | analytics | tag_managers | … → one row per entity. Without group_by: one aggregate; set metrics return top categories.
| Name | Type | Req | Description |
|---|---|---|---|
| filter | object | – | AND filters. Omit for all sites in the dataset. Keys: device (all|phone|desktop), cms, framework, cdn, provider (key), provider_category (e.g. analytics — use with provider or alone is not enough; pr… |
| focus | string | – | CWV used when correlating technique metrics. Default: lcp. |
| group_by | string | – | Break results down by this dimension: cms, frameworks, cdn, or a provider category (analytics, tag_managers, …). Omit for a single aggregate. |
| limit | integer | – | Max groups or top categories. Default: 25, max: 100. |
| metrics | – | – | Metrics to return. Default: lcp,inp,cls,ttfb,good_all3. String (comma-separated) or array of strings. |
| min_sites | integer | – | When group_by is set, drop groups with fewer sites. Default: 50. |
No output schema declared.
No examples provided.
list_options ~90
Discover what you can pass to get_metrics / get_histogram: filter keys, group_by values, built-in metrics, and contract metric paths (optional kind filter). Call this when unsure of a key or path.
| Name | Type | Req | Description |
|---|---|---|---|
| include_paths | boolean | – | Include full contract path list. Default true. |
| kind | string | – | Optional contract kind: scalar, boolean, categorical, set, weighted_set, measures. |
No output schema declared.
No examples provided.
What is the State of Web Vitals MCP server?
State of Web Vitals is an MCP server listed in the public MCP registry as io.github.corewebvitals/state-of-cwv. Core Web Vitals metrics by CMS, CDN, and framework, free remote MCP, no auth. This page covers its hosted endpoint (https://www.corewebvitals.io/api/state-of-cwv/mcp).
Is the State of Web Vitals MCP server safe to use?
State of Web Vitals scores 83 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the State of Web Vitals MCP server expose?
State of Web Vitals exposes 3 tools: get_metrics, get_histogram, list_options. Their descriptions and schemas cost roughly 694 tokens of context every time the server is loaded.
Does the State of Web Vitals MCP server require authentication?
No. We connected to State of Web Vitals without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the State of Web Vitals MCP server still maintained?
State of Web Vitals is still listed as active in the MCP registry. We last reached this channel on 22 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.