Yab, Yet Another Browser
NPM · YAB-MCP
Your own signed-in Mac browser for any agent: open, read and act in tabs. Local and free.
Available components
Last scanned (7 hours ago)
Scores higher than 58% of npm servers
Category Browser Automation
How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. How we score → Why this is hard to score →
Supply Chain Security100
- No malware found by supply-chain analysis.Pass
- No known CVEs affecting this package version or its production dependencies.Pass
- No install/post-install scripts declared.Pass
- No production dependencies, so there is no dependency health to assess. View diagnostics → Pass
Provenance & Transparency45
- Source repository is publicly reachable at the declared URL. View diagnostics → Pass
- Provenance check failed: no build-provenance attestation is published. See how to fix → View diagnostics → Fail
- Clear OSI-approved license (MIT).Pass
- Actively maintained (last published 14 days ago).Pass
- Disclosure check failed: no security disclosure policy was found in the source repository. See how to fix → Fail
Schema Quality & AI Usability66
- AI-judged instruction clarity (good).Pass
- Context-footprint check failed: tool/resource definitions use about 7490 tokens (~108/item across 69 items; 69 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 Management73
- Stability observed for 22 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage81
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 44% of tool parameters carry a description.Partial
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- All 4 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation.Pass
- An AI judge read all 70 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
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.
- 5 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 70 to 73. That category is still filling its 30-day observation window: 21 days of observed history at the previous scan, 22 at this one. The score rises as the window fills, whether or not the server changes.
- 3 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 63 to 67. That category is still filling its 30-day observation window: 19 days of observed history at the previous scan, 20 at this one. The score rises as the window fills, whether or not the server changes.
- 1 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 57 to 60. That category is still filling its 30-day observation window: 17 days of observed history at the previous scan, 18 at this one. The score rises as the window fills, whether or not the server changes.
- 30 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 50 to 53. That category is still filling its 30-day observation window: 15 days of observed history at the previous scan, 16 at this one. The score rises as the window fills, whether or not the server changes.
- 28 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 43 to 47. That category is still filling its 30-day observation window: 13 days of observed history at the previous scan, 14 at this one. The score rises as the window fills, whether or not the server changes.
- 25 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.
- 23 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.
- 21 Oct 26 +4
- Stability: unverified → 0.23 ▲ functional
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 5 Nov 2026 · Analysed npm/yab-mcp@0.2.1
Provenance No attestation
The registry publishes no build provenance for this version, so there is nothing to verify.
| Result | No attestation |
|---|---|
| Ecosystem | npm |
Background: How many MCP packages publish verified provenance →
Dependencies 0 packages
| Packages resolved | 0 |
|---|---|
| Tree resolution | Complete |
Background: SBOMs and build attestations, explained →
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 →
send_message Send Message ~46
Send a message through Messages to a phone number or an address. The user sees the whole text first and says yes.
| Name | Type | Req | Description |
|---|---|---|---|
| text | string | yes | – |
| to | string | yes | – |
No output schema declared.
No examples provided.
show Show Tab ~126
Put a tab in front of the user as one of theirs: yours comes out of this task's folder, stays after the task, in the space it is signed in to. Call it when the user asked you to open or show them a page ("open their page", "show me the PR"), once the tab is that page; never for pages you only read. It is theirs after it: don't act in it again. A tab of the user's is only brought to the front.
| Name | Type | Req | Description |
|---|---|---|---|
| tab | string | yes | Tab id, as `open` or `tabs` gave it |
No output schema declared.
No examples provided.
sign_in Sign In ~123
Sign in on this tab's page with a password Yab has saved for the site (the user may be asked first). The password is filled by Yab and never shown to you. user picks the account when Yab keeps several (it says which). Call again for the next step (a password page after a name page). If Yab has none, call handoff.
| Name | Type | Req | Description |
|---|---|---|---|
| tab | string | yes | Tab id, as `open` or `tabs` gave it |
| user | string | – | The account's name or email, when there are several |
No output schema declared.
No examples provided.
skill Read a Skill ~22
Read one skill whole, by name.
| Name | Type | Req | Description |
|---|---|---|---|
| name | string | yes | – |
No output schema declared.
No examples provided.
skills List Skills ~52
Yab's skills: how particular sites work for an agent (Gmail, GitHub, LinkedIn, Amazon, …), a line each. When you land on a site that has one, the answer says so.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
snapshot Read Page ~146
Read a web page in a browser tab as an accessibility tree with ref ids. interactive (default true) lists what can be clicked, typed into, hovered or scrolled, headings and status messages; false gives the whole page's text structure. ref narrows it to one element's subtree. Other sites' frames (payment forms) are read in place, their refs like f1e3. A ref keeps naming its element while it is on the page.
| Name | Type | Req | Description |
|---|---|---|---|
| interactive | boolean | – | – |
| ref | string | – | Element ref from the latest snapshot, e.g. e12 |
| tab | string | yes | Tab id, as `open` or `tabs` gave it |
No output schema declared.
No examples provided.
spaces List Spaces ~95
List the user's spaces: sets of tabs, some signed in as someone else, with cookies of their own. With site, says for each whether the user is signed in to that site there: ask it before ever telling the user they are signed out of a site. `open` and `fetch` without space already go where the site is signed in.
| Name | Type | Req | Description |
|---|---|---|---|
| site | string | – | A site, as github.com or a URL |
No output schema declared.
No examples provided.
suggest Suggest on New Tab ~81
Hand the user what needs them, as quiet rows under a new tab's field (most urgent first; four show), and say which rows already there are dealt with. Only when a task asked you to look for such things.
| Name | Type | Req | Description |
|---|---|---|---|
| items | array | yes | – |
| resolved | array | – | Ids of rows already on the new tab that are dealt with now |
No output schema declared.
No examples provided.
tabs List Tabs ~50
List the tabs open in Yab, the user's web browser: the user's and the agents'. Yours can always be acted in; the user's as they allow, and the one in front of them never sent elsewhere.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
task Run Task ~135
Hand a whole browser job to an agent Yab runs itself (Claude Code, or Codex), and wait for its answer. Cheaper on your context than driving tabs step by step. Pass `session` to continue an earlier task with a follow-up.
| Name | Type | Req | Description |
|---|---|---|---|
| access | string | – | browser (default): only Yab's tabs; full: request files and terminal access before the task starts (Ask/Auto ask the person; Bypass skips the question) |
| cli | string | – | – |
| effort | string | – | – |
| model | string | – | – |
| prompt | string | yes | – |
| session | string | – | – |
No output schema declared.
No examples provided.
task_queue Queue for Task ~35
Give a task something to do after what it is doing now.
| Name | Type | Req | Description |
|---|---|---|---|
| session | string | yes | – |
| text | string | yes | – |
No output schema declared.
No examples provided.
task_status Task Status ~30
What a task is doing now, and its answer when it is done.
| Name | Type | Req | Description |
|---|---|---|---|
| session | string | yes | – |
No output schema declared.
No examples provided.
task_steer Steer Task ~38
Redirect a running task now: it reads this at its next step.
| Name | Type | Req | Description |
|---|---|---|---|
| session | string | yes | – |
| text | string | yes | – |
No output schema declared.
No examples provided.
task_stop Stop Task ~19
Stop a task.
| Name | Type | Req | Description |
|---|---|---|---|
| session | string | yes | – |
No output schema declared.
No examples provided.
text Read Page Text ~40
A tab's whole visible text, for reading articles and results.
| Name | Type | Req | Description |
|---|---|---|---|
| tab | string | yes | Tab id, as `open` or `tabs` gave it |
No output schema declared.
No examples provided.
type Type ~108
Replace the text in a field by ref (inputs, text areas, editors), or without ref, type into whatever has focus (after clicking into a field in a frame, say). submit: true presses Enter after. Returns what changed.
| Name | Type | Req | Description |
|---|---|---|---|
| ref | string | – | Element ref from the latest snapshot, e.g. e12 |
| submit | boolean | – | – |
| tab | string | yes | Tab id, as `open` or `tabs` gave it |
| text | string | yes | – |
No output schema declared.
No examples provided.
upload Upload Files ~103
Give the page files from this Mac (the user may be asked first): ref is what attaches a file (Attach, a paperclip, a file field). Paths are absolute or ~/…; nothing hidden, at most 100 MB a file.
| Name | Type | Req | Description |
|---|---|---|---|
| files | array | yes | – |
| ref | string | – | Element ref from the latest snapshot, e.g. e12 |
| tab | string | yes | Tab id, as `open` or `tabs` gave it |
No output schema declared.
No examples provided.
wait Wait for Page ~57
Wait for a tab to finish loading, or until its text contains `for`.
| Name | Type | Req | Description |
|---|---|---|---|
| for | string | – | – |
| seconds | number | – | – |
| tab | string | yes | Tab id, as `open` or `tabs` gave it |
No output schema declared.
No examples provided.
watch Watch for a Reply ~120
Watch a thread for someone's reply: every two hours for `days` (default 3), Yab quietly checks it and, when the reply comes, puts it on the user's new tab. Call it after you send something the user is waiting to hear back on, or when they ask to know about a reply. With stop and an id, ends a watch.
| Name | Type | Req | Description |
|---|---|---|---|
| days | number | – | – |
| stop | string | – | – |
| url | string | – | The thread's own address |
| who | string | – | Whose reply, a name |
No output schema declared.
No examples provided.
How do I install the Yab, Yet Another Browser MCP server?
Yab, Yet Another Browser runs locally as an npm package, launched with npx -y yab-mcp. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
npm · yab-mcp
claude mcp add com-yetanotherbrowser-yab -- npx -y yab-mcp
What is the Yab, Yet Another Browser MCP server?
Yab, Yet Another Browser is an MCP server listed in the public MCP registry as com.yetanotherbrowser/yab. Your own signed-in Mac browser for any agent: open, read and act in tabs. Local and free. This page covers its npm package (yab-mcp).
Is the Yab, Yet Another Browser MCP server safe to use?
Yab, Yet Another Browser scores 78 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 5 November 2026. It declares no install or post-install scripts. 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 Yab, Yet Another Browser MCP server expose?
Yab, Yet Another Browser exposes 69 tools: devtools_comments, devtools_console, devtools_network, devtools_trace, devtools_styles, and 64 more. Their descriptions and schemas cost roughly 7,444 tokens of context every time the server is loaded.
Is the Yab, Yet Another Browser MCP server still maintained?
Yab, Yet Another Browser is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.
What licence is the Yab, Yet Another Browser MCP server under?
Yab, Yet Another Browser declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.