Build Plugin

Build Plugin

Bundle many tools (skills, hooks, agents, MCP servers) into one installable Claude Code plugin and distribute it. The defining move of this skill: establish who the plugin is for and where it will live with AskUserQuestion before assembling anything, then tailor every phase to that answer. A personal one-project bundle and a public team marketplace share almost nothing past "assemble", so branch early and commit to the branch.

How this relates to build-mcp

build-mcp builds one MCP server: analyze a service, implement the tools, deploy, scale. build-plugin bundles many tools (including MCP servers produced by build-mcp) into a single shareable unit and distributes it. When build-mcp reaches its Distribute phase for a team or public audience, it hands off here: packaging into a plugin and listing it on a marketplace is this skill's job. Use build-mcp to make a server, then build-plugin to ship it alongside your skills, hooks, and agents.

The four phases

1. Analyze: decide what tools go in the bundle, and name it.
2. Assemble: build the plugin folder and manifest, test it locally with claude --plugin-dir.
3. Ship: put it on a marketplace repo, on the right git host, public or private, with one-click enablement for a team.
4. Maintain: versions, updates, ownership, and admin controls.

Run them in order. The AskUserQuestion answers from Phase 0 gate Ship and Maintain.

Phase 0: Establish context (AskUserQuestion, do this first)

Before assembling anything, branch on the user's context. Ask the audience question first; it is the headline decision and it cascades into everything downstream. Then ask the git host only if it is still ambiguous. Ask one question at a time.

Question 1 (always, ask first): Audience:

Use AskUserQuestion:

• header: "Audience"
• question: "Who is this plugin for? This decides where it's hosted and how it's shared."
• options:
  1. "Just me": personal bundle of my own tools, one machine or a couple of projects.
  2. "My team / org": shared internally, installed by colleagues.
  3. "Public / external": published openly for anyone to install.

Question 2 (conditional, skip for "Just me"): Git host:

Skip entirely for "Just me" (no remote needed). Ask for team or public:

• header: "Git host"
• question: "Where will the marketplace repo live?"
• options:
  1. "GitHub": unlocks the owner/repo shorthand and Anthropic's public directory.
  2. "GitLab or other git host": works via the full https://...git URL, no GitHub mirror needed.
  3. "Not sure yet": decide during Ship; GitHub is the smoothest default.

Confirm the resolved tuple back to the user in one line before proceeding (e.g. "Bundling a team plugin of three skills plus one MCP server, hosted on a private GitHub marketplace repo"). That tuple drives the branch table below.

Branch table (the spine of this skill)

If a cell says "N/A, stop here" for the chosen branch, say so explicitly and move on. Do not pad it. The Enable row is the team-facing half of Ship (turning the marketplace on for colleagues), not a separate phase.

Reference files:

• references/assemble.md: plugin folder layout, the manifest fields, moving existing ~/.claude/ tools in, local claude --plugin-dir testing, skill namespacing, claude plugin validate.
• references/marketplace.md: the marketplace.json shape, per-host source types, add and install commands, public vs private and auth.
• references/team-enablement.md: project .claude/settings.json auto-enable, org-wide managed-settings enforcement.
• references/maintain.md: updates, version bumps, ownership, fixes via merge request.

Load only the references the current branch and phase need. Progressive disclosure.

Phase 1: Analyze

Decide what goes in the bundle before you build the folder.

1. Inventory the tools. List every skill, hook, agent, and MCP server the plugin should carry. A plugin can hold any mix; each type sits in its own place in the layout (see assemble.md).
2. Draw the boundary. One plugin is one coherent unit that updates together. If two groups of tools serve different audiences or version on different clocks, that is two plugins.
3. Name it. Kebab-case, distinct, describes the bundle not one tool inside it. The name becomes the skill namespace (/my-plugin:skill) and the marketplace entry key.
4. Note what already exists loose. Tools sitting in ~/.claude/skills, ~/.claude/agents, or a personal settings.json will move into the plugin and the loose originals get deleted, so you do not run duplicates (assemble.md covers this).

Deliverable: the plugin name plus a list of what it will contain. Confirm with the user before assembling.

Phase 2: Assemble

Read references/assemble.md. Build the folder to the layout, write the manifest, then test locally.

1. Create the plugin dir. Only plugin.json goes inside .claude-plugin/; skills/, agents/, hooks/hooks.json, and .mcp.json sit at the plugin ROOT.
2. Write .claude-plugin/plugin.json with name, description, version, author.
3. Move the inventoried tools in and delete the loose originals.
4. Validate, then load-test. claude plugin validate . checks the manifest and layout with no login. claude plugin details <name> lists the skills, hooks, and servers it discovered, also login-free. claude --plugin-dir ./my-plugin (it also accepts a .zip) loads it into a live session so you can invoke a tool; that one needs you logged in.

For a "Just me" bundle this is the last substantive phase: it is loaded, it works, stop.

Phase 3: Ship

Only for team or public. Read references/marketplace.md, and references/team-enablement.md for the auto-enable path. Branch on the git-host answer.

1. Create the marketplace repo, or reuse an existing one. Add .claude-plugin/marketplace.json at its root with name, owner, and a plugins[] entry for this plugin.
2. Set the entry source by host: relative "./path" if the plugin lives in the same repo, {source:"github", repo:"owner/repo"} for GitHub, or {source:"url", url:"https://...git"} for GitLab, Bitbucket, or self-hosted. There is no gitlab source type.
3. Choose public vs private to match the audience. A private repo keeps a team plugin internal; a public repo is installable by anyone who knows it, running arbitrary code with the user's privileges, so make that choice deliberately.
4. Confirm the install path a colleague runs: /plugin marketplace add owner/repo (GitHub shorthand) or the full https://...git URL for any other host, then /plugin install name@marketplace.

Phase 4: Maintain

Read references/maintain.md. Branch lightly; the mechanics are the same across hosts.

1. Updates. Users pull new versions with /plugin marketplace update or at startup.
2. Version boundary. Bump version in plugin.json so users get a clean update boundary; omit it and Claude Code treats every commit SHA as a new version.
3. Ownership. One maintainer per plugin. Fixes land via merge request, since the source is a git repo.
4. Org controls (team/public, admin job). Force-install, an allowlist (strictKnownMarketplaces), or a denylist (blockedMarketplaces) live in a managed-settings file, set by an admin, not per user (team-enablement.md).

Done criteria

• The plugin validates (claude plugin validate) and its tools show up (claude plugin details); loading it via claude --plugin-dir in a session invokes at least one.
• It is on a marketplace repo the resolved audience can reach, public or private matching that audience (or, for "Just me", it is loaded locally and there is no marketplace).
• The user can name exactly how a colleague installs it, two-command or one-click, matching the audience answer.