05 — MCP
Native Model Context Protocol client and server support. A curated registry of trusted MCP servers. One-line install UX. The agent extends itself the same way Claude Code, Crush, Kimi, Cline, and Tabnine extend themselves — through the open standard everyone now ships against.
What MCP gives us
MCP servers extend the agent with outside tools. Picasso loads them on demand: each server is reached through one <server>_call gateway tool (or tool_call), so its tool list costs nothing until it is used, and a direct <server>_call runs on the current engine. MCP config changes reach the next session; Streamable HTTP and stdio transports are supported.
| Command | Effect | ||||||
|---|---|---|---|---|---|---|---|
picasso mcp search <query> / install <server-id> | Find and install from the signed registry. | ||||||
picasso mcp apps | The apps you can connect, with what each reaches and reads. | ||||||
picasso mcp add [name] (--command or --url) / remove <name> | Connect an app, or add or remove a server by hand. | ||||||
picasso mcp list / enable / disable / validate / logs | Manage installed servers. | ||||||
| `/mcp list\ | add\ | remove\ | install\ | enable\ | disable\ | validate [id]` | The same in the TUI; /mcp add [app] [--yes]. |
Connect an app
Picasso for Mac's Connect an app (Extensions) and picasso mcp apps offer Blender, Figma, browser automation, Xcode, iOS Simulator and x.md. Each lists the hosts it reaches and the keys it reads. x.md is the only remote one, and it is labelled third-party.
Extension cost and data access
Every plugin, MCP server and skill shows a measured per-turn cost: what it adds to every turn and what it adds only when used, for example "Every turn 142 tokens · On demand 1.2k tokens". Above 3,000 tokens Picasso warns ("These add 4.2k tokens to every turn."). Each also shows its data access ("Reaches: <hosts> · Reads: <keys>"). The first install or turn-on of a third-party plugin or app asks once ("It comes from a third party, not Picasso. Picasso asks once."); the CLI and TUI need --yes for it.
- Mac: Extensions (cost and access per item; Add index saves a market index).
- CLI:
picasso extensions list,picasso extensions plugin <package>(admission-gated;--yeson a first third-party install),picasso extensions plugins. - TUI:
/extensions list.
Runtime note
MCP connections run inside the engine; Picasso's installed-server store and signed registry are Picasso plugins. See architecture.