Registry Files

MCP servers are defined in two places:

• registry/mcp-servers.json — server definitions (command, args, env)
• registry/config.json — target config and optional server toggles

In a checkout, edit these files directly. With the published package, they ship as packaged defaults.

User Registry

In the cards-era store, user-registered MCP servers live as one JSON file per server:

~/.agents/bgng/mcp-servers/<server-id>.json

Add a user MCP server:

bgng library add mcp my-server.json --as my-server

Machine-wide active MCP defaults live in ~/.agents/bgng/machine.json under defaults.mcpServers.

Pre-cards installs used ~/.agents/library/mcp-servers.json. bgng store migrate explodes that legacy file into the cards-era mcp-servers/ directory and archives the old layout.

Inspecting MCP State

bgng mcp list
bgng mcp list --json

Writing MCP Config

Preview before writing:

bgng mcp write --dry-run

Write to all targets:

bgng mcp write

Limit to one target:

bgng mcp write --target=cursor

Notes

• Platform-provided entries can live in the registry but are excluded from generated local tool configs
• Optional servers are included only when enabled in registry/config.json
• Parallel MCP is controlled by config.parallel.mcp.enabled
• Card-provided servers and project-local server overrides apply when commands run inside a configured project
• Project-local extension settings such as extensions.parallel.mcp are applied when commands run inside that project