The plugin has three parts. .mcp.json points Claude Code at SerpApi's hosted MCP server. The userConfig entry in .claude-plugin/plugin.json makes Claude Code ask each user for their API key. skills/search/ holds the instructions Claude follows to choose engines and parameters. Everything in this folder ships to users, so keep it small.
claude plugin validate --strict .
claude plugin validate --strict .claude-plugin/plugin.jsonThe first command checks only marketplace.json. The second checks the plugin itself, including .mcp.json, its ${user_config.*} references, and the skill. CI runs both on every push and pull request.
To try a change, add your local copy as a marketplace and install from it. The install asks for an API key:
/plugin marketplace add /absolute/path/to/serpapi-claude-plugin
/plugin install serpapi@serpapi-plugins
Check that /mcp shows plugin:serpapi:serpapi as connected, then run a search. Each test search uses one search from your plan.
When you start Claude Code inside this repository, it also offers the repository's .mcp.json as a project MCP server named serpapi and asks you to approve it. Decline it. That copy can't read the plugin's API key, and the installed plugin already provides the server.
Raise version in .claude-plugin/plugin.json. The marketplace entry has no version of its own. Before submitting to Anthropic's plugin directory, run Validate in the developer portal and work through the pre-submission checklist.