Implement an Agent Plugins client

A conformant client loads an Agent Plugin from a directory, validates plugin.json, and supports at least one component type: skills or MCP servers.

Loading sequence

1. Establish the filesystem-resolved plugin root.
2. Locate and validate root plugin.json using the locally supported schema selected by $schema.
3. Reject the plugin for fatal manifest violations; report and ignore the explicitly non-fatal cases.
4. Discover each supported component type from its fixed location.
5. Apply the failure boundary defined for each component type or entry.
6. Apply implemented client-extension namespaces and ignore all others.

Clients use canonical schema identifiers to select local validation and interpretation rules. They do not retrieve schemas while loading a plugin.

Portable versus client-owned behavior

Agent Plugins defines package structure, validation, discovery, MCP configuration, plugin variables, and failure isolation. It does not prescribe:

• installation sources, registries, or marketplaces
• enablement, update, or cache user experience
• permission prompts, trust policy, or sandboxing
• how skills are shown to users or models
• internal client-extension behavior

Next steps

• Loading and discovery — Validate the manifest, discover supported components, and apply failure boundaries.
• MCP runtime — Map portable MCP configuration to stdio and HTTP connections.
• Conformance checklist — Check the minimum portable client requirements.