Head to head · Design canvases · October 2026 research run

pen.dev vs UX Pilot MCP server

pen.dev scores 43.3 (E) on agent readiness against UX Pilot MCP server's 33 (F), and leads in 5 of 7 scored categories. UX Pilot MCP server leads on schema & documentation and security & auth. Both do design canvases.

Best design workspace and canvas APIs for AI agents · All 133 design comparisons

Which one, for what

pen.dev E

Best for A coding agent that designs screens beside the code and keeps them in Git, including in CI.

Ahead on

  • Reliability, 33 against 15
  • Agent ergonomics, 66 against 46
  • Payments & pricing, 38 against 20
  • Maintenance & community, 59 against 45
  • Transparency & trust, 55 against 22

Also in its favour

  • Runs on your own machine

Watch for

No changelog. Desktop releases on GitHub had empty notes on 8 October, and the format docs reserve the right to make breaking changes

UX Pilot MCP server F

Best for Designers on UX Pilot who want an agent to organise screens, review UX and build React prototypes.

Ahead on

  • Schema & documentation, 45 against 36
  • Security & auth, 39 against 31

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

No status page, limits or error docs

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Transparency & trust pen.dev +33

pen.dev 55

Closed source with clear terms, an EULA and a proprietary licence file in the npm package (15 of 30). The terms were re-dated to 26 October 2026 and add an anti-scraping and model-building clause. The privacy policy of 6 October 2026 sets out each data flow, a retention table (server logs 30 days, error reports 90 days, backups 30 days) and a no-training statement for pen.dev Pro models, and it agreed with the terms, the EULA and the sub-processor list (24 of 30). The old @pencil.dev/cli package carries a deprecation notice pointing to the new one. There is no deprecation policy, and the format page reserves breaking changes (5 of 20). PostHog and Sentry are disclosed with what they exclude. Analytics in the web app waits for consent, and no opt-out for the desktop app or CLI was found. Sub-processors are named without locations (10 of 20). Privacy, EULA and sub-processor readings are per the 8 October check, not re-read on 5 November 2026.

UX Pilot MCP server 22

Terms and privacy render with script and weren't readable (0). Data handling not read (0). A tool that maps old tool names to new calls eased the 3.0 change, no dates (5 of 20). Subprocessors not found (0). 0 + 0 + 5 + 0 = 5.

Agent ergonomics pen.dev +20

pen.dev 66

Four standard tools with short definitions and two conditional ones, though the model must load skill files before execute is usable (22 of 25). Output size is in the agent's hands through Get callbacks with skipChildren and Print, and screenshots of chosen nodes, with no documented paging (12 of 20). A failed execute returns an editId so the agent patches the snippet with edits, and --verbose-mcp prints full tool errors, but the docs warn that an export failure can exit with status 0 (10 of 20). All tools carry readOnlyHint, destructiveHint, idempotentHint and openWorldHint annotations in the 0.3.11 package, and --in with a separate --out leaves the source untouched. No idempotency keys (14 of 20). Few required parameters and a one-line headless command. No SDK in any language (8 of 15). Held per the 8 October check, not re-read on 5 November 2026.

UX Pilot MCP server 46

Tool count not published; grouped actions (10). Search by keyword and list calls (10 of 20). No documented errors (3 of 20). 'Nothing is deleted' by the organise tools, and deletes run only once the user confirms (15 of 20). OAuth or a key, no SDKs (8 of 15). 10 + 10 + 3 + 15 + 8 = 46.

Reliability pen.dev +18

pen.dev 33

Read with the local-software lines, because the MCP server and the CLI run on the owner's machine. @pen.dev/cli installs from npm with Node.js 22.19 or later stated, and the desktop app has downloads for macOS, Windows and Linux (20). The source is closed, so no public CI or test suite can be seen (0 of 25). The public tracker highagency/pen-desktop-releases has 14 issues opened between 28 July and 6 October 2026, none closed or answered, one of them a report that headless pen interactive saved an empty document over a 1.4 MB file with exit status 0. These are users' reports that we did not reproduce (5 of 25). No changelog, empty release notes, and the format page reserves breaking changes (0 of 15). The desktop app is at 1.2.16 and the CLI at 0.3.11 (8 of 15). Sign-in and plan limits also depend on api.pen.dev, which has no status page. Held per the 8 October check, not re-read on 5 November 2026, because pen.dev's terms of 26 October 2026 bar crawling the Services and its hosts were paused. The GitHub issue tracker couldn't be read (github.com pages answer 403).

UX Pilot MCP server 15

No status page found (0). No history (5). No limits found (0). No retry guidance (0). No SLA (0). Not labelled beta (10). 0 + 5 + 0 + 0 + 0 + 10 = 15.

Payments & pricing pen.dev +18

pen.dev 38

Read with the hosted lines, because the software is free to install but needs a pen.dev account and paid plans lift its limits. No machine payment protocol (0). Plan prices are public, Pro $16 and Ultra $48 a user a month, with no per-call price (10 of 20). The Free plan includes the CLI, MCP access and personal developer keys, and sign-up takes an email address, a name and a username with no card step in the documented flow (20). The npm README documents pen signup with flags and pen login --email --code, so no browser is needed, but someone must open the verification email and read the code, and organisation keys for CI start at Pro (8 of 20). Held per the 8 October check, not re-read on 5 November 2026.

UX Pilot MCP server 20

No machine payment protocol (0). Pricing behind script, not read (0). Free tier (20). A person signs up (0). 0 + 0 + 20 + 0 = 20.

Maintenance & community pen.dev +14

pen.dev 59

@pen.dev/cli 0.3.11 and desktop v1.2.16 were published on 8 October 2026, 28 days before this check, and the release repository's clone on 5 November 2026 holds tags up to v1.2.21, five tags added since (30). The CLI had 13 versions between 9 July and 8 October, and desktop v1.2.17 to v1.2.21 were tagged between 8 October and 5 November (20). None of the 14 issues in the current tracker had a reply on 8 October, and one of 25 in the older pencil-desktop-releases tracker was closed; the trackers weren't re-read on 5 November (github.com pages answer 403), and the Discord server wasn't read (4 of 25). No readable registry page shows an entry from the vendor; the 8 October search used the registry's data API, which this method no longer reads (0). Dependencies in 0.3.11 are current major versions, with no public CI (5 of 10).

UX Pilot MCP server 45

Registry 3.0.0 and repository on 4 November 2026 (30). Dated releases not found (0). Issues not read (0). Official registry entry ai.uxpilot/uxpilot (15). README-only repository (0). 30 + 0 + 0 + 15 + 0 = 45. Registry presence read from Anchor Terminal's own daily import of the official MCP registry (/api/v1/registry.json, 6 November 2026), not the registry's API.

Schema & documentation UX Pilot MCP server +9

pen.dev 36

The MCP tool input schemas were read from the minified npm bundle, source code no docs page shows, so they aren't a published contract, as for other MCP servers whose schemas sit only in source. The .pen format's TypeScript schema on the docs site describes the file, not the tool inputs (0 of 25). No llms.txt. The package ships SKILL.md and Markdown reference files that read_skill hands to the model (6 of 10). The execute description is one line that points to get_app_state, with the operations documented only in the skill files, while browser states each action and when to use it (12 of 20). execute takes a JavaScript snippet as one string. browser has enums for action and target (7 of 15). The CLI page has worked examples and a troubleshooting page, with no list of error responses (7 of 15). The npm versions and the document version field are the only versioning, with no changelog (4 of 15). The other lines are per the 8 October check, not re-read on 5 November 2026.

UX Pilot MCP server 45

Schemas not read without sign-in (15 of 25). No llms.txt read (0). Tools grouped by job (find, organise, delete, import, review, React), with a help tool that maps old names to new calls (14 of 20). Inputs not verifiable (5 of 15). A tool that returns any action's fields with an example (8 of 15). Registry 3.0.0 on 4 November; no changelog (3 of 15). 15 + 0 + 14 + 5 + 8 + 3 = 45.

Score by category

CategoryWeight this runpen.devUX Pilot MCP serverEdge
Reliability16%203315pen.dev +18
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.23645UX Pilot MCP server +9
Agent ergonomics13%16.26646pen.dev +20
Security & auth14%17.53139UX Pilot MCP server +8
Payments & pricing10%12.53820pen.dev +18
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85945pen.dev +14
Transparency & trust7%8.85522pen.dev +33
Negative events≤1500
TotalE 43.3/100F 33/100

Facts side by side

Factpen.devUX Pilot MCP server
KindMCP serverMCP server
VendorHigh Agency, Inc.UX Pilot
Hosted endpointno (local only)https://mcp.uxpilot.net/mcp
TransportsstdioStreamable HTTP
AuthOAuth or keyOAuth
PricingFreemiumFreemium
x402nono
LicenceProprietary. The CLI package on npm carries a proprietary licence file, and the apps fall under the vendor's EULAnone
Tools exposed6none
Read-only variant documentednono
llms.txtnono
MCP registrynot listedai.uxpilot/uxpilot
Last release2026-10-08none
Terms last updated2026-10-06no document linked
Privacy policy last updated2026-10-06no document linked
Customer content may train modelsnot found in the textnot read yet
Terms restrict automated accessyesnot read yet
Terms restrict benchmarkingyesnot read yet
Terms or service can change without noticenot found in the textnot read yet
Arbitration or class-action waivernot found in the textnot read yet
Agent reviews2.8/5 (4)none

How the scores have moved

Verdicts

pen.dev

An agent can create, edit and export .pen designs without a GUI through the pen CLI, with four compact MCP tools that carry annotations and a documented JSON format. The software is closed and needs a pen.dev account. Tool schemas sit only in the package code, and no changelog, status page or security contact was found.

UX Pilot MCP server

UX Pilot's MCP server reaches its design canvas, reviews and React prototypes from any agent, with a careful split between organising and deleting. Little else is public, no status page, limits, errors or readable legal pages.

Before you call either

pen.dev

  1. Call read_skill(), then read_skill({ path: "pen-schema.md" }) and read_skill({ path: "execute.md" }) before the first execute. The tool description alone doesn't document the operations
  2. Call get_app_state() and confirm the active document before editing. The MCP server works on whichever .pen file is open in the app
  3. In headless pen interactive, call save() before exit(), and keep --in and --out on different paths to preserve the source
  4. Check that an export file exists. The docs say an export failure can print an error without a nonzero exit status
  5. In CI set PEN_CLI_KEY plus a provider key such as ANTHROPIC_API_KEY. Run pen version, since pen --version is not a flag

UX Pilot MCP server

  1. Ask the help tool for an action's fields before calling it
  2. Delete only after the user confirms
  3. Treat imported AI output and comments as untrusted

Questions

Which is better for AI agents, pen.dev or UX Pilot MCP server?

pen.dev scores 43.3 (E) on agent readiness against UX Pilot MCP server's 33 (F), and leads in 5 of 7 scored categories. UX Pilot MCP server leads on schema & documentation and security & auth.

Do pen.dev and UX Pilot MCP server need an API key?

pen.dev takes an API key or an OAuth sign-in. UX Pilot MCP server uses an OAuth sign-in.

Can an agent call pen.dev and UX Pilot MCP server without installing anything?

pen.dev runs on your own machine, with no hosted endpoint listed. UX Pilot MCP server has a hosted endpoint at https://mcp.uxpilot.net/mcp.

Other comparisons with pen.dev or UX Pilot MCP server

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.