Documentation

A Harness Pack is three files that describe a CLI you already ship, so a person, an agent and a product UI all run it as one governed command. Pick the page for what you do and start there.

Choose your path#

Build a pack

You ship a CLI and want agents, people, and product UIs to run it as one governed command.

Implement a runtime

You build the product that loads packs, enforces grants, and runs them under your own auth.

Adopt in a host

You make an agent product and want it to install packs as easily as it adds an MCP server.

Evaluate HCP

You want to know what HCP is, which problem it solves, and where it sits beside Agent Skills and MCP.

Set up your agent#

Every host gets one Skill and one tool named hcp that reaches every pack you activate, or your agent can do the whole setup from one prompt.

Terminal

hcpx activate transit ledger
hcpx adopt claude --write       # .claude/skills/hcp + one hcp server in .mcp.json

On its next start, Claude Code asks you to approve the hcp server in the project .mcp.json. The Skill also teaches it to run hcp from its shell.

Claude Code setup in detail

Look something up#

Concepts explains the objects every call passes through, and Design principles the twelve laws behind them. For lookups, the CLI reference has every hcpx command and exit code, Manifest fields every surface.json field, Pack classes five shapes to copy, the glossary every term, and the specification what packs, runtimes and hosts must do.

For agents#

Every page has a Markdown twin: append .md to the URL or send Accept: text/markdown. The full corpus is at /llms.txt and /llms-full.txt, search at /api/v1/search?q=, and a read-only MCP server at /mcp offers list_pages, search, and get_page.