CtrlK
BlogDocsLog inGet started
Tessl Logo
SkillPublic

cua-spaces

Work inside cua Spaces through the cua MCP server. A Space is a remote or local computer the user can watch; you can run commands in it, move files in and out, show its desktop or a single window on the user's screen, start coding agents inside it, teleport a signed-in app session into it, and share the host's network with it. Use when the user mentions Spaces, asks you to do work "in a Space", or wants a task isolated but visible.

Quality

89%

Does it follow best practices?

Run evals on this skill

Adds up to 20 points to the overall score

View guide
SecuritybySnyk

Low

Low-risk findings worth noting

SKILL.md
Quality
Evals
Security

Quality

Content

90%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

Excellent instructional content: dense, token-efficient tool tables and copy-paste-ready commands with no filler, plus a properly sequenced host-setup procedure with approval checkpoints. The only gaps are minor — no verification steps around create/delete_space and an ssh setup procedure that could be split into a reference file.

DimensionReasoningScore

Conciseness

The body is lean and assumes competence: tool tables carry one-line descriptions, the host-setup procedure gives exact commands with no preamble, and there is no explanation of concepts Claude already knows (e.g., 'Tailscale is only the ssh transport, the same as any LAN or internet address' is a one-line product-specific clarification, not padding). Every token carries cua-specific information, matching anchor 5.

5 / 5

Actionability

Guidance is copy-paste ready throughout: 'curl -fsSL https://cua.ai/install.sh | sh -s -- -y --select spaces,host --no-onboarding', 'cua auth login --remote', 'cua host setup --share spaces --name "<name>"', 'cua spaces create macos:26 --on "<name>" --count 2', 'cua share space:dev:3000', plus exact tool parameters like create_space(on="host:<name>", count=2) and on = local|aws|gcp|modal|host:<name>. Per the scoring notes, an instruction-only skill with this level of concrete guidance matches anchor 5.

5 / 5

Workflow Clarity

The host setup is a clear 6-step numbered sequence with an explicit approval checkpoint (show the device code and URL, have the user approve), and risky operations have checkpoints (teleport_manifest with explicit acknowledgement before teleport_app; open a link once to check it works before sending). It falls short of anchor 5 because the day-to-day flow is presented as tool tables rather than a sequenced workflow, and there is no verify step after create_space or before the destructive delete_space.

4 / 5

Progressive Disclosure

Sections are well-organized and scannable (Get a Space / Work in it / Show it / Agents, apps and network / ssh host setup / Rules / Links), with no nested or buried references and nothing that is bulky reference material inlined. It does not reach anchor 5 — the ~90-line body exceeds the under-50-line simple-skill exception and the specialized ssh host-setup procedure (~25 lines) is inlined where a one-level reference file could carry it — but anchor 4's 'good structure, most content appropriately placed, minor organization gaps' fits.

4 / 5

Total

18

/

20

Passed

Description

83%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description: it states what the skill does through six concrete, comprehensive actions and gives an explicit 'Use when' clause with natural trigger phrases. Its only deductions are the second-person voice ('you can run commands in it') and a few missing natural synonyms around the isolation/remote-machine intent.

Suggestions

Rewrite in third person to reclaim the specificity penalty — e.g., 'Runs commands in a Space, moves files in and out, shows its desktop or a single window on the user's screen...' instead of 'you can run commands in it'.

DimensionReasoningScore

Specificity

The description lists six concrete, comprehensive actions ("run commands in it, move files in and out, show its desktop or a single window... start coding agents inside it, teleport a signed-in app session into it, and share the host's network"), fully matching anchor 5's comprehensive coverage — but the second-person phrasing "you can run commands in it" triggers the rubric's 1-point voice penalty, bringing it to 4.

4 / 5

Completeness

Both halves are explicit: a clear multi-action 'what' ("Work inside cua Spaces through the cua MCP server... run commands in it, move files in and out...") followed by concrete trigger phrases in a 'Use when...' clause ("Use when the user mentions Spaces, asks you to do work 'in a Space', or wants a task isolated but visible"). This matches anchor 5 exactly; anchor 4's 'when could be more explicit' does not apply.

5 / 5

Trigger Term Quality

Natural triggers are well covered: "the user mentions Spaces", "asks you to do work 'in a Space'", "wants a task isolated but visible", plus the product name "cua Spaces". It falls short of anchor 5's comprehensive synonym coverage (e.g., no 'remote machine', 'cloud computer', or 'sandbox' variations), so 4 fits better than 5.

4 / 5

Distinctiveness Conflict Risk

The distinct product term 'cua Spaces' and its quoted trigger phrases give it a clear niche, but the intent-based trigger "wants a task isolated but visible" could plausibly overlap with generic sandbox/VM/isolation skills — minor overlap risk with closely related skills, matching anchor 4 rather than anchor 5's minimal conflict risk.

4 / 5

Total

17

/

20

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository

trycua/cua

Path

libs/cua/skills/cua-spaces/SKILL.md

Reviewed

Table of Contents

Is this your skill?

If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.