io.github.cyanheads/browser-compat-mcp-server
REMOTE · BROWSER-COMPAT.CASEYJHAND.COM · 2 COMPONENTS · SCANNED SEP 21
Browser compatibility and Baseline status for any web feature — offline, from bundled MDN data.
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 Security66
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation not fully verified: no authorisation is required to call this server, and 5 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe. See how to fix → View diagnostics → Unverified
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- DNSSEC is configured correctly; the domain's records validate against the full chain to the root. View diagnostics → Pass
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability68
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 1269 tokens (~253/item across 5 items; 5 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 Management0
- Stability not yet verified: not enough scan history yet (needs a 30-day window).Unverified
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
- Structured output schemas are declared (100% of tools); any adoption earns full credit.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
Unverified: 1 category
A category scored 0 because we could not verify it: authentication we do not have, an unreachable endpoint, or not enough scan history. We only credit what we can confirm.
How do I install the io.github.cyanheads/browser-compat-mcp-server server?
io.github.cyanheads/browser-compat-mcp-server is a hosted endpoint at https://browser-compat.caseyjhand.com/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 · browser-compat.caseyjhand.com
claude mcp add --transport http cyanheads-browser-compat-mcp-server 'https://browser-compat.caseyjhand.com/mcp'
{
"mcpServers": {
"cyanheads-browser-compat-mcp-server": {
"url": "https://browser-compat.caseyjhand.com/mcp"
}
}
} {
"servers": {
"cyanheads-browser-compat-mcp-server": {
"type": "http",
"url": "https://browser-compat.caseyjhand.com/mcp"
}
}
} [mcp_servers.cyanheads-browser-compat-mcp-server] url = "https://browser-compat.caseyjhand.com/mcp"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"cyanheads-browser-compat-mcp-server": {
"type": "remote",
"url": "https://browser-compat.caseyjhand.com/mcp",
"enabled": true
}
}
} openclaw mcp add cyanheads-browser-compat-mcp-server --url 'https://browser-compat.caseyjhand.com/mcp' --transport streamable-http
mcp_servers:
cyanheads-browser-compat-mcp-server:
url: "https://browser-compat.caseyjhand.com/mcp" {
"McpServers": {
"cyanheads-browser-compat-mcp-server": {
"Transport": "http",
"Url": "https://browser-compat.caseyjhand.com/mcp"
}
}
} assistant mcp add cyanheads-browser-compat-mcp-server -t streamable-http -u 'https://browser-compat.caseyjhand.com/mcp'
{
"mcpServers": {
"cyanheads-browser-compat-mcp-server": {
"type": "http",
"url": "https://browser-compat.caseyjhand.com/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.
- 20 Sept 26 67
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 20 Sept 2026 · Probed https://browser-compat.caseyjhand.com/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=caseyjhand.com | CN=WE1,O=Google Trust Services,C=US | 4 Sept 2026 | 3 Dec 2026 | ECDSA 256 | ECDSA-SHA256 | a6985204ed51ae050e7738aa6be668e9 |
| SANs: caseyjhand.com, *.caseyjhand.com | ||||||
| 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 secure
Validation of browser-compat.caseyjhand.com. — Secure
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| com. | present | 19718 | 13 | Verified |
| caseyjhand.com. | present | 2371 | 13 | Verified |
| browser-compat.caseyjhand.com. | Verified address RRset verified with the apex keys |
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 |
| x-content-type-options | nosniff |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://browser-compat.caseyjhand.com/mcp | Verified | 200 | |
| http (plaintext) | http://browser-compat.caseyjhand.com/mcp | HTTPS enforced | 301 | https://browser-compat.caseyjhand.com/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 →
browsercompat_check_baseline Browsercompat Check Baseline ~196
Check whether web features are safe to ship: Baseline state and the date it crossed, the browser and version that limits support, whether the feature is deprecated or discouraged, and the share of tracked global traffic that requiring it would exclude. Accepts up to 20 BCD keys or web-features ids in one call.
| Name | Type | Req | Description |
|---|---|---|---|
| features | array | yes | Up to 20 entries, each a browser-compat-data key such as css.selectors.has or a web-features id such as has, 1 to 200 characters. An empty or longer entry is rejected against this schema; a whitespac… |
| resolve | boolean | – | When true, fall back to the search index and accept its single unambiguous top hit for each entry. Off by default so a typo returns a miss you can correct. |
| Name | Type | Req | Description |
|---|---|---|---|
| all_widely_available | boolean | – | True only when every entry resolved and reports Baseline widely. A single miss forces false. Deprecation and discouragement do not enter this answer. |
| attribution | string | – | Required attribution for the caniuse-derived usage figures in this response. |
| data_version | object | – | Vintage of each bundled dataset behind this answer. |
| error | object | – | Present when the call failed. Absent on success. |
| results | array | – | One result per requested feature. A miss is a result, not a failure. |
| totalCount | number | – | Number of results returned. |
| unresolvedNotice | string | – | Names the entries that did not resolve and how to find the right key. |
No examples provided.
browsercompat_compare_support Browsercompat Compare Support ~261
Compute whether a set of web features clears an explicit browserslist target query. Returns a per-feature verdict, the target browser and version that fails, the share of tracked traffic the targets cover, and unchecked_targets for every resolved target browser with no compatibility data. A feature is never reported as clearing a target the server could not evaluate.
| Name | Type | Req | Description |
|---|---|---|---|
| features | array | yes | Up to 20 entries, each a browser-compat-data key such as css.selectors.has or a web-features id such as has, 1 to 200 characters. An empty or longer entry is rejected against this schema; a whitespac… |
| resolve | boolean | – | When true, fall back to the search index and accept its single unambiguous top hit for each entry. Off by default so a typo returns a miss you can correct rather than a confident answer about the wro… |
| targets | string | yes | A browserslist query, for example "defaults" or "> 0.5%, last 2 versions", 1 to 500 characters. Required: with no query browserslist would read config from the process working directory rather than f… |
| Name | Type | Req | Description |
|---|---|---|---|
| all_clear | boolean | – | True only when every feature clears and unchecked_targets is empty. |
| attribution | string | – | Required attribution for the caniuse-derived coverage figures in this response. |
| data_version | object | – | Vintage of each bundled dataset behind this answer. |
| error | object | – | Present when the call failed. Absent on success. |
| query_echo | string | – | The targets query as the server parsed it. |
| results | array | – | Per-feature verdicts against the resolved targets. |
| target_coverage_percent | number | – | Share of tracked global traffic the evaluated targets cover. |
| targets_resolved | array | – | Every browserslist token that was evaluated. |
| totalCount | number | – | Number of feature results returned. |
| uncheckedNotice | string | – | Names the target agents that were not evaluated and their combined usage share. |
| unchecked_coverage_percent | number | – | Share of tracked global traffic the unevaluated targets cover. |
| unchecked_targets | array | – | Every target the server declined to claim a verdict for, with the reason. |
No examples provided.
browsercompat_get_feature Browsercompat Get Feature ~254
Get the compatibility record for one web feature: Baseline state and the date it crossed, deprecation and standards status, per-browser version added and removed with flags, vendor prefixes and partial-implementation notes, and the MDN and specification links. Accepts a BCD key such as css.selectors.has or a web-features id such as has; the response echoes which one it matched. An unresolved feature returns found: false with guidance rather than an error.
| Name | Type | Req | Description |
|---|---|---|---|
| feature | string | yes | A browser-compat-data key such as css.selectors.has, or a web-features id such as has, 1 to 200 characters. An empty or longer string is rejected against this schema; a whitespace-only string returns… |
| include_runtimes | boolean | – | Add the bun, deno, nodejs, and oculus rows to support. Leave off for browser ship decisions. |
| resolve | boolean | – | When true, fall back to the search index and accept its single unambiguous top hit. Off by default so a typo returns a miss you can correct rather than a confident answer about the wrong feature. |
| Name | Type | Req | Description |
|---|---|---|---|
| baseline | object | – | Baseline state for the resolved key, or the feature rollup when a web-features id resolved to more than one key. |
| baselineNotMapped | string | – | Explains why a resolved key carries no Baseline state. |
| compat_keys | array | – | Present when the web-features id spans more than one browser-compat-data key. Call this tool again with one of them for the per-browser fields. |
| data_version | object | – | Vintage of each bundled dataset behind this answer. |
| description | string | – | web-features description, or the browser-compat-data description with tags stripped. |
| error | object | – | Present when the call failed. Absent on success. |
| found | boolean | – | True when the feature string resolved to a tracked entry. |
| guidance | string | – | What to do next on a miss or with no compat data. |
| limiting_browser | object | – | Among the Baseline core browsers, the one requiring the newest release. Absent until every core browser has shipped a resolvable version. |
| mdn_url | string | – | MDN reference page for the resolved key. |
| name | string | – | web-features display name for the feature. |
| outcome | string | – | found when per-feature data was returned, no_compat_data when the entry is tracked but owns no browser-compat-data keys, miss when nothing matched. |
| resolved_as | – | – | How the feature string was matched, or null on a miss. |
| runtimesExcluded | string | – | Notes that the feature carries server-runtime or XR data that was left out. |
| spec_urls | array | – | Specification URLs for the resolved key, always an array. |
| status | object | – | Standards status for the resolved key. Absent for webextensions keys, which record none, and when the id spans more than one key. |
| support | array | – | One row per reported browser. Absent when the id spans more than one browser-compat-data key. |
No examples provided.
browsercompat_list_reference Browsercompat List Reference ~161
Enumerate the reference vocabulary this server uses: BCD namespaces, BCD browser ids, browserslist agent ids and their BCD counterparts, Baseline states, web-features groups, and ECMAScript snapshots. Use it to build valid inputs for the other tools and to see which target browsers can be evaluated.
| Name | Type | Req | Description |
|---|---|---|---|
| topic | string | yes | Which vocabulary to list: bcd_namespaces for the 12 top-level browser-compat-data namespaces, bcd_browsers for the 17 tracked browsers, browserslist_agents for the 19 browserslist ids mapped to brows… |
| Name | Type | Req | Description |
|---|---|---|---|
| attribution | string | – | Required attribution for the caniuse-derived usage figures in this response. |
| data_version | object | – | Vintage of each bundled dataset behind this answer. |
| entries | array | – | Every entry in the requested vocabulary. |
| error | object | – | Present when the call failed. Absent on success. |
| topic | string | – | The topic that was listed. |
No examples provided.
browsercompat_search_features Browsercompat Search Features ~168
Find web features by plain name or keyword when the canonical key is unknown, across CSS, JavaScript, HTML, Web APIs, SVG, MathML, WebAssembly, and HTTP headers. Returns ranked matches with the BCD key, the web-features id, the Baseline state, a one-line support summary, and which field matched. Feed a result key into browsercompat_get_feature for the full record.
| Name | Type | Req | Description |
|---|---|---|---|
| baseline | string | – | Restrict results to one Baseline state. |
| limit | integer | – | Maximum results to return, from 1 to 50. |
| namespace | string | – | Restrict results to one top-level browser-compat-data namespace. |
| query | string | yes | Plain-language name or keyword, for example "container query" or "fromAsync". |
| Name | Type | Req | Description |
|---|---|---|---|
| appliedFilters | object | – | Filters the server applied to this search. |
| cap | number | – | The limit that was applied. |
| data_version | object | – | Vintage of each bundled dataset behind this answer. |
| error | object | – | Present when the call failed. Absent on success. |
| noMatchNotice | string | – | How to broaden a search that matched nothing. |
| results | array | – | Ranked matches, best first. An empty array is a successful search with no hits. |
| shown | number | – | Number of results returned. |
| totalCount | number | – | Matches before the display cap was applied. |
| truncated | boolean | – | True when matches exceeded limit. |
No examples provided.
What is the io.github.cyanheads/browser-compat-mcp-server server?
io.github.cyanheads/browser-compat-mcp-server is listed in the public MCP registry as io.github.cyanheads/browser-compat-mcp-server. Browser compatibility and Baseline status for any web feature, offline, from bundled MDN data. This page covers its hosted endpoint (https://browser-compat.caseyjhand.com/mcp).
Is the io.github.cyanheads/browser-compat-mcp-server server safe to use?
io.github.cyanheads/browser-compat-mcp-server scores 67 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 io.github.cyanheads/browser-compat-mcp-server server expose?
io.github.cyanheads/browser-compat-mcp-server exposes 5 tools: browsercompat_list_reference, browsercompat_get_feature, browsercompat_check_baseline, browsercompat_search_features, browsercompat_compare_support. Their descriptions and schemas cost roughly 1,040 tokens of context every time the server is loaded.
Does the io.github.cyanheads/browser-compat-mcp-server server require authentication?
No. We connected to io.github.cyanheads/browser-compat-mcp-server without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the io.github.cyanheads/browser-compat-mcp-server server still maintained?
io.github.cyanheads/browser-compat-mcp-server is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.