FSB vs MCP Browser Kit
A side-by-side look at the FSB and MCP Browser Kit MCP servers: transport, auth, tools, quality signals, and the config to install either one in Claude, Cursor, Windsurf or VS Code.
Verdict: choose FSB for browser automation work as a local process; choose MCP Browser Kit for browser automation as a local process. You can also run both side by side in one mcpServers block.
Which MCP server should you choose?
Choose FSB when
- You need dedicated capabilities in the Browser Automation domain.
- You prefer a local stdio subprocess transport.
- Its auth model fits you: No auth required.
- You want tools like
start_visual_session, end_visual_session, trigger.
Choose MCP Browser Kit when
- You need dedicated capabilities in the Browser Automation domain.
- You prefer a local stdio subprocess transport.
- Its auth model fits you: No auth required.
- You want tools like
captureTab, invokeJsFn, openTab.
Feature & specification comparison
Rows where the two servers differ are marked.
| Spec | ||
|---|---|---|
| Category | Browser Automation | Browser Automation |
| Quality signal | 64/100 · Good | 67/100 · Great |
| Install command | Confirmed | Confirmed |
| Transport | Local subprocess (stdio) | Local subprocess (stdio) |
| Auth | No auth required | No auth required |
| Pricing | Free | Free |
| Required env vars | None listed | None listed |
| Verified owner | Community listing | Community listing |
| GitHub stars | 202 | 55 |
| Directory activity | 1 views 0 installs 0 upvotes | 3 views 0 installs 0 upvotes |
| Tools | 72 | 19 |
| Full listing | View FSB | View MCP Browser Kit |
Tools & capabilities
FSB tools 72
start_visual_session[REMOVED in v0.9.0] This tool was removed in fsb-mcp-server v0.9.0 (FSB v0.9.62 implicit visual-session contract). Calling it returns the typed TOOL_REMOVED error with a migration recipe pointer. The visual session is now implicit on every action tool call via the required visual_reason + client field bundle -- there is no longer a separate start call. See CHANGELOG.md#v0.9.0 and the Visual Session Lifecycle section of mcp/README.md for the migration recipe.end_visual_session[REMOVED in v0.9.0] This tool was removed in fsb-mcp-server v0.9.0 (FSB v0.9.62 implicit visual-session contract). Calling it returns the typed TOOL_REMOVED error with a migration recipe pointer. The visual session now clears either automatically after 60 seconds of silence (sliding window) or immediately when an action tool is called with is_final: true -- there is no longer a separate end call. See CHANGELOG.md#v0.9.0 and the Visual Session Lifecycle section of mcp/README.md for the migration recipe.triggerArm a reactive DOM trigger on one selector. Use this when the user wants to watch an element until it changes, crosses a threshold, equals or matches a value, or contains text. The watch is owned by the background trigger runtime and persisted across service-worker eviction. Pass one selector and one condition object; runtime validation checks the nested condition details before arming. Use stop_trigger to cancel, get_trigger_status to inspect one watcher, and list_triggers to enumerate watchers.stop_triggerCancel a trigger by id. This is cancellation-critical and bypass-class: it must be callable promptly even if a trigger or another mutation is pending. Missing or already terminal triggers are handled idempotently by the background trigger runtime.get_trigger_statusRead the persisted status for one trigger by id. Returns storage-of-truth trigger state including status, watch mode, condition, target tab, owner, current value, timing, and attention details when available.list_triggersList persisted trigger snapshots. By default, returns active and attention-state watchers; include_terminal can include fired and stopped triggers for audit or cleanup workflows.execute_jsRun JavaScript directly in the active page. PRIMARY INTERACTION TOOL: try execute_js FIRST for clicks, scrolls, reads, attribute lookups, and most other DOM work -- it bypasses overlay/obscured-element issues, viewport constraints, and CDP timeouts that block native click/scroll. Typical patterns: `return document.querySelector('#add-to-cart-button').click(), true;` for clicks; `return Array.from(document.querySelectorAll('a')).map(a=>a.href);` for extraction; `window.scrollTo(0, document.body.scrollHeight); return true;` for scroll. After a JS click, verify with read_page or get_page_snapshot (a true click should produce observable DOM change). FALLBACK TO NATIVE TOOLS WHEN: (1) JS click reports success but the page state did not change (framework swallowed the synthetic event -- use native click which fires real CDP events that React/Angular/Vue listen to); (2) typing into controlled text inputs (use native `type` so React onChange fires correctly -- `element.value = ...` will NOT update component state); (3) real drag operations on react-beautiful-dnd / Sortable.js / Trello-style widgets (use drag_drop / drag for real pointer events); (4) form submission that depends on validated input state (use native click on submit). Code runs as a function body -- use `return` to send values back (results are stringified). Async work: Promises are not awaited, so fire-and-forget then poll on `window.__yourKey`. Related: read_page (verify result), get_dom_snapshot (debug after JS click), click / type / drag_drop (fallbacks when JS doesn't take effect). Multi-agent: agent-scoped tabs; cross-agent reject with TAB_NOT_OWNED; cap configurable (default 8, 1-64). Pass tab_id only when this agent owns multiple tabs; auto-resolves otherwise. RETURNS change_report: when this tool runs, the response includes a `change_report` field with a compact diff of what the action mutated (URL, dialogs_opened, nodes_added, nodes_removed, attrs_changed, inputs_changed, focus_shift). Use this to learn the consequence without calling read_page next. If the report exceeds the size cap, `change_report.truncated:true` and `change_report_hint` are set; call read_page for the full state.navigateOpen a URL in the active browser tab. Returns the final URL after any redirects. When to use: as the first step to reach a target website. Related: read_page (read content after navigating), list_tabs (see what tabs are already open). Multi-agent: agent-scoped tabs; cross-agent reject with TAB_NOT_OWNED; cap configurable (default 8, 1-64). Pass tab_id only when this agent owns multiple tabs; auto-resolves otherwise. RETURNS change_report: when this tool runs, the response includes a `change_report` field with a compact diff of what the action mutated (URL, dialogs_opened, nodes_added, nodes_removed, attrs_changed, inputs_changed, focus_shift). Use this to learn the consequence without calling read_page next. If the report exceeds the size cap, `change_report.truncated:true` and `change_report_hint` are set; call read_page for the full state.searchSearch for content on the current site or web. When to use: to find content on the current site or web. Automatically detects the site's search input (Amazon, YouTube, GitHub, etc.) via DOM heuristics -- only falls back to Google when no site search exists. Returns search results status. Related: read_page (read search results after searching), click (click a specific search result). Multi-agent: agent-scoped tabs; cross-agent reject with TAB_NOT_OWNED; cap configurable (default 8, 1-64). Pass tab_id only when this agent owns multiple tabs; auto-resolves otherwise.go_backNavigate back one page in browser history. Returns the new URL. When to use: to return to the previous page after following a link or navigating away. Related: go_forward (undo a go_back), navigate (go to a specific URL instead). Multi-agent: agent-scoped tabs; cross-agent reject with TAB_NOT_OWNED; cap configurable (default 8, 1-64). Pass tab_id only when this agent owns multiple tabs; auto-resolves otherwise. RETURNS change_report: when this tool runs, the response includes a `change_report` field with a compact diff of what the action mutated (URL, dialogs_opened, nodes_added, nodes_removed, attrs_changed, inputs_changed, focus_shift). Use this to learn the consequence without calling read_page next. If the report exceeds the size cap, `change_report.truncated:true` and `change_report_hint` are set; call read_page for the full state.go_forwardNavigate forward one page in browser history. Returns the new URL. When to use: after using go_back, to move forward again. Related: go_back (go back in history), navigate (go to a specific URL instead). Multi-agent: agent-scoped tabs; cross-agent reject with TAB_NOT_OWNED; cap configurable (default 8, 1-64). Pass tab_id only when this agent owns multiple tabs; auto-resolves otherwise. RETURNS change_report: when this tool runs, the response includes a `change_report` field with a compact diff of what the action mutated (URL, dialogs_opened, nodes_added, nodes_removed, attrs_changed, inputs_changed, focus_shift). Use this to learn the consequence without calling read_page next. If the report exceeds the size cap, `change_report.truncated:true` and `change_report_hint` are set; call read_page for the full state.refreshReload the current page. Returns the refreshed URL. When to use: when page content may be stale, after errors, or to reset page state. Related: navigate (go to a different URL), wait_for_stable (wait for page to settle after refresh). Multi-agent: agent-scoped tabs; cross-agent reject with TAB_NOT_OWNED; cap configurable (default 8, 1-64). Pass tab_id only when this agent owns multiple tabs; auto-resolves otherwise. RETURNS change_report: when this tool runs, the response includes a `change_report` field with a compact diff of what the action mutated (URL, dialogs_opened, nodes_added, nodes_removed, attrs_changed, inputs_changed, focus_shift). Use this to learn the consequence without calling read_page next. If the report exceeds the size cap, `change_report.truncated:true` and `change_report_hint` are set; call read_page for the full state.- +60 more on the listing page
MCP Browser Kit tools 19
captureTabScreenshot a tab. When: MV2 tabs only; you need pixel coordinates for coordinate tools. How: browserId, windowId, tabId from bk:///context; use returned dimensions to compute x/y. Requires: browserId, windowId, tabId. Returns: value { data (base64 image), width, height, mimeType } — use width/height to scale coordinates. Avoid: calling on manifestVersion 3 — use readable-elements instead.invokeJsFnExecute a JavaScript function body in the page context. When: MV2 only, and only when element/coordinate tools cannot accomplish the task — e.g. setting a native <select> (.value then dispatch change) or a range slider. How: fnBodyCode is the function body only (no function wrapper); use return to send a value back. Example: return document.title; Requires: browserId, windowId, tabId, fnBodyCode. Returns: value.result = whatever you return (must be JSON-serializable). Avoid: on manifestVersion 3; wrapping in function () { ... }.openTabOpen a URL in a new tab. When: navigating to a page not already open. How: browserId and windowId from bk:///context; url must include scheme (https://); after success re-read context for the new tabId and wait for page load. Requires: browserId, windowId, url. Returns: value { browserId, windowId, tabId } — use the returned ids for follow-up calls. Avoid: interacting immediately — tab needs a moment to load.closeTabClose a tab. Irreversible. When: finished with a tab and no further interaction needed. How: browserId, windowId, tabId from bk:///context. Requires: browserId, windowId, tabId. Returns: ok=true once closed. Avoid: closing the tab you still need for further interactions.getSelectionGet the user's current text selection in a tab. When: you need text the user has highlighted on the page. How: browserId, windowId, tabId from bk:///context. Requires: browserId, windowId, tabId. Returns: value.selectedText — empty string when nothing is selected. Avoid: expecting content when nothing is selected.clickOnCoordinatesClick at pixel coordinates inside a tab. When: MV2 fallback when no readablePath is available. How: x/y from a recent captureTab screenshot (same width/height); browserId, windowId, tabId from context. Requires: browserId, windowId, tabId, x, y. Returns: ok=true on success; on ok=false re-capture the tab and recompute x/y. Avoid: on MV3 (no screenshot source); prefer clickOnElement when readablePath exists.fillTextToCoordinatesClick at (x, y) then type text into the focused input. When: MV2 fallback for inputs without a readablePath. How: coordinates from recent captureTab; submit via clickOnCoordinates on submit button or hitEnterOnCoordinates. Requires: browserId, windowId, tabId, x, y, value. Returns: ok=true on success; on ok=false re-capture the tab and recompute x/y. Avoid: on MV3; prefer fillTextToElement when readablePath is available.hitEnterOnCoordinatesClick at (x, y) then press Enter to submit a form. When: MV2 fallback to submit when no submit button readablePath exists. How: coordinates from recent captureTab. Requires: browserId, windowId, tabId, x, y. Returns: ok=true on success; on ok=false re-capture the tab and recompute x/y. Avoid: on MV3; prefer hitEnterOnElement when readablePath is available.clickOnElementClick an element by readablePath. When: primary click method on MV2 and MV3. How: read {tabUri}/readable-elements; filter [path, role, text, value?] tuples by role and text; copy path exactly (e.g. 0.2.1) — not a CSS selector. Custom dropdown/combobox/datepicker: click the trigger to open it, then re-read readable-elements and click the option/day cell. Native <select>: clicking an option can work for listbox selects (multiple or size>1) but single-line dropdowns use a native popup that ignores synthetic clicks — those need invokeJsFn (MV2) or showHumanHint (MV3). Verify by re-reading and escalate. See Complex inputs. Requires: browserId, windowId, tabId, readablePath. Returns: ok=true on success; on ok=false re-read readable-elements and pick a fresh path. Avoid: inventing paths; re-read elements after navigation if click fails.fillTextToElementType text into an <input> or <textarea> by readablePath. When: primary fill method on MV2 and MV3. Also handles native <input> date/time/datetime-local/month/color when value is in the exact format (date YYYY-MM-DD, time HH:MM, datetime-local YYYY-MM-DDTHH:MM, month YYYY-MM, color #rrggbb). How: readablePath from first element of [path, role, text, value?] tuple in readable-elements; submit via clickOnElement on submit button or hitEnterOnElement. Requires: browserId, windowId, tabId, readablePath, value. Returns: ok=true on success; on ok=false re-read readable-elements and pick a fresh path. Avoid: CSS selectors as readablePath; stale paths after DOM changes. Does not work on contenteditable rich-text editors (MV2 invokeJsFn instead), native <select>, or custom popup dropdowns/datepickers — use the strategy ladder under Complex inputs in server instructions.hitEnterOnElementFocus an element by readablePath then press Enter. When: submitting a form when no explicit submit button exists. How: readablePath from readable-elements tuple (dot-separated index like 0.2.1). Requires: browserId, windowId, tabId, readablePath. Returns: ok=true on success; on ok=false re-read readable-elements and pick a fresh path. Avoid: using when a submit button readablePath is available — click it instead.scrollPageScroll the page viewport in a direction. When: target content or elements are off-screen; reveal more of the page before reading or interacting. Works on MV2 and MV3 (no screenshot needed). How: direction is up/down/left/right; optional amount in pixels — omit it to scroll ~one viewport (a page). browserId, windowId, tabId from bk:///context. Requires: browserId, windowId, tabId, direction. Returns: ok=true once scrolled. Already at that edge (nothing to scroll) is still ok=true. Avoid: assuming new elements exist — re-read readable-elements after scrolling, snapshots go stale.- +7 more on the listing page
Ready-to-paste client configs
Paste either block (or both) into your client config, e.g. claude_desktop_config.json or ~/.cursor/mcp.json. We only show a config when the install command is confirmed.
FSB
{
"mcpServers": {
"fullselfbrowsing-fsb": {
"command": "npx",
"args": [
"-y",
"fsb-mcp-server@latest"
]
}
}
}
MCP Browser Kit
{
"mcpServers": {
"ndthanhdev-mcp-browser-kit": {
"command": "npx",
"args": [
"-y",
"@mcp-browser-kit/server@latest"
]
}
}
}
Frequently asked questions
FSB is categorized under Browser Automation and uses a local stdio subprocess. MCP Browser Kit belongs to Browser Automation and uses a local stdio subprocess. Pick FSB for browser automation work and MCP Browser Kit for browser automation.
Copy the mcpServers block from the config section on this page into your client's config (for example claude_desktop_config.json or ~/.cursor/mcp.json), then fully restart the client.
FSB is listed as free. Auth: no auth required. MCP Browser Kit is listed as free. Auth: no auth required. If a server needs environment variables such as API keys, define them under the env key in your client's MCP config.
Yes. MCP clients support multiple servers: add fullselfbrowsing-fsb and ndthanhdev-mcp-browser-kit as separate keys in the same mcpServers object, and your assistant will call tools from either one.
On AllMCPs, FSB has a quality signal of 64/100 (Good) with 1 views, 0 installs and 202 GitHub stars. MCP Browser Kit has 67/100 (Great) with 3 views, 0 installs and 55 GitHub stars.
