Arc Free Skills — Claude Code MCP server
A hundred skills for systems and hardware engineers: requirements review, interface checks, power and mass budgets, verification evidence. Runs as a local MCP server.
claude mcp add arc-free-skills -e ARC_FREE_SKILLS_WORKSPACE=<ARC_FREE_SKILLS_WORKSPACE> -- uvx arc-free-skillsWhat Arc Free Skills does
Arc Free Skills ships 100 task-specific skills for systems and hardware work. Review a requirement against an ECSS edition, check an electrical or mechanical interface, roll up a power or mass budget, map required environmental conditions to test evidence, hunt missing failure modes in an FMEA, build a verification matrix, diff two versions of a spec. Some skills target airborne electronic hardware and DO-254 assurance records.
The repo holds a skill catalogue plus a local MCP server. You point the agent at a file and it loads the matching skill with its references. A setup prompt does the wiring for you: installs locked dependencies, connects the MCP, confirms skill discovery, creates an arc-engineering-work folder for inputs and outputs. Web chat has no local MCP, so the skill instructions get attached to the conversation and the chat's own file tools do the reading.
Local setup wants Python 3.11+ and uv. No model API key is involved. ARC_FREE_SKILLS_WORKSPACE must point at your working folder, since the server needs to know where input files live and where results go.
What it helps with
- clean up a requirements spreadsheet and map its fields before import
- pull requirements out of a customer PDF with page references
- flag requirements that contradict each other in one specification
- size power demand by operating mode and leave the margin visible
- match DO-254 assurance records to the applicable objectives
Example prompts for the agent
- Clean and map
customer-requirements.xlsx, keep every source ID and original statement, then show the field mapping and duplicate IDs. - Build a power budget from
component-loads.xlsx, separating standby, nominal and peak demand by operating mode, and show the remaining margin.
How to install Arc Free Skills
Platform CLI
claude mcp add arc-free-skills -e ARC_FREE_SKILLS_WORKSPACE=<ARC_FREE_SKILLS_WORKSPACE> -- uvx arc-free-skillsReplace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from arc-free-skills <command>
Platform CLI
codex mcp add arc-free-skills --env ARC_FREE_SKILLS_WORKSPACE=<ARC_FREE_SKILLS_WORKSPACE> -- uvx arc-free-skillsReplace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from arc-free-skills <command>
Config file
{
"mcpServers": {
"arc-free-skills": {
"command": "uvx",
"args": [
"arc-free-skills"
],
"env": {
"ARC_FREE_SKILLS_WORKSPACE": "<ARC_FREE_SKILLS_WORKSPACE>"
}
}
}
}Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from arc-free-skills <command>
Config file
{
"servers": {
"arc-free-skills": {
"type": "stdio",
"command": "uvx",
"args": [
"arc-free-skills"
],
"env": {
"ARC_FREE_SKILLS_WORKSPACE": "<ARC_FREE_SKILLS_WORKSPACE>"
}
}
}
}Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from arc-free-skills <command>
Platform CLI
gemini mcp add -e ARC_FREE_SKILLS_WORKSPACE=<ARC_FREE_SKILLS_WORKSPACE> arc-free-skills uvx arc-free-skillsReplace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from arc-free-skills <command>
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about Arc Free Skills
How do I install Arc Free Skills in Claude Code?
Register the server with claude mcp add arc-free-skills -e ARC_FREE_SKILLS_WORKSPACE=<ARC_FREE_SKILLS_WORKSPACE> -- uvx arc-free-skills. The other form spells out the transport: claude mcp add --env ARC_FREE_SKILLS_WORKSPACE=<ARC_FREE_SKILLS_WORKSPACE> --transport stdio arc-free-skills -- uvx arc-free-skills.
What does Arc Free Skills actually do?
It hands your agent 100 engineering skills covering requirements, interfaces, budgets, qualification tests and verification. The agent picks the right one and works on your own files: specs, spreadsheets, test reports.
What do I need to run it locally?
Python 3.11+ and uv, plus a folder path for ARC_FREE_SKILLS_WORKSPACE where inputs sit and outputs land. No model API key.
