BC x-mirror
x-mirror is a comprehensive mirror source management tool for various package managers. Use this skill whenever users need to configure, switch, or query package manager download mirrors. This skill handles: setting up and switching mirrors for package managers (pip, npm, brew, apt, go, cargo, gem, etc.), viewing available mirror options, checking current mirror configuration, restoring default official sources, and optimizing download speeds in China regions. Triggered by queries like "set npm mirror", "change pip source", "npm mirror speed", "pip Tsinghua mirror", "brew Chinese mirror", "x mirror apt", "how to speed up npm download", "configure pip mirror", "switch npm registry", or any request related to package manager mirrors, registry settings, or download acceleration. This skill is essential for developers in China or anyone needing to optimize package download speeds.
As a process C 60/100 · Has gaps — weak spots: result and completion, failures and branches, progress reporting
What is at stake
The skill contains fragments that, in the wrong hands, cost money or data. Below: what the installer risks and what the author should do.
The skill contains commands that delete files, rewrite disks or execute code fetched from the network. The agent may run them without asking if it believes the instructions require it.
Replace destructive commands with safe equivalents that ask for confirmation, scope them to one folder, and stop piping curl into a shell: pin a version and a checksum.
How to improve
- Address the high-severity findings: each costs 18 safety points. If one is a false positive, add the rule id to guard.allow in spec.yaml.
- Your own cases (evals/evals.json, 4–6 real requests with expected answers): the full check would then run those instead of a model-drafted suite.
- A spec.yaml with trigger phrases and assertions — a behaviour contract for CI; `skilltest init` writes a template.
Guard findings · 2
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high Dangerous commands
cmd-pipe-to-shelldata/install.md:104Downloads and executes remote code from an unrecognised host (pipe to shell)curl -fsSL https://get.x-cmd.com | sh
Medium and low: 1
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medium Dangerous commands
cmd-pipe-to-shelldata/install.md:25Downloads and executes remote code from an unrecognised host (pipe to shell) (quoted — discussed, not commanded)command: "curl -fsSL https://get.x-cmd.com | sh"
quoted
Files scanned: 3. Evidence is masked. Grey chips explain why severity was lowered.
Against the Agent Skills spec
✓ No remarks against the Agent Skills spec
Process rating: all ten parameters 60/100
- 0Result and completion. Does not say what the result is
- 0Failures and branches. Linear process with no failure handling
- 0Progress reporting. Says nothing while it works
- 60Tools and files. Uses tools (bash, python) that frontmatter does not declare
- 70When it triggers. States when to use, but not when not to
- 70Inputs and preconditions. Inputs and preconditions are listed
- 100Steps. 10 steps
- 100Consistency. Name and required fields are in place
- 100Execution cost. Instruction body is 451 tokens
- 100Running it twice. No mutating operations
Everything here is measured from the skill text rather than judged by a model, so the numbers are checkable. A parameter weighs more when it is a more common reason for the process to stall.
Quality signals
- +4Description does not say when NOT to use the skill (false activations)
- +3Description length 889: 120–800 characters recommended
- +3Output format is not stated: the model decides each time
- +2Single-language instructions
- +5Description quotes 9 example trigger phrases
- +4Structure: 14 headings
- +3Step-by-step instructions: 10 items
- +4Has examples (5 code blocks)
- +1License stated
Quality base 70; lint remarks subtract, signals add up to 100. Result: 87.