Solo exposes MCP tools through the local MCP server configured in Settings > Integrations > MCP. Compatible clients launch Solo's bundled stdio helper, and the running Solo app enforces which tools are available.
This section is a tool reference. For setup steps and client configuration, see MCP server integration.
Core tool groups
Core tools are available when the MCP server is enabled:
- Project tools choose the effective Solo project, create, rename, and delete projects, and inspect project state.
- Workspace tools list, create, edit, delete, and reorder workspaces, and move projects between them.
- Services tools discover localhost services and wait for ports.
- Process tools list, inspect, select, rename, start, stop, restart, close, and send input to Solo processes.
- Bulk tools provide project-scoped batch operations to start trusted commands, stop running commands regardless of trust, or restart by first stopping running commands and then starting trusted commands.
- Output tools read, search, clear, and inspect terminal output and ports.
- Agent and terminal tools spawn terminals or agents, bind MCP sessions to Solo-managed processes, and manage agent tool configurations.
- Coordination tools provide project-scoped lease locks for shared work.
- Setup and support tools provide local help, search Solo's official documentation, summarize the enabled tool catalog, run a smoke test, draft feedback, and write agent integration instructions.
Feature tool groups
Feature tools are turned on from each feature's own settings page. They augment the same MCP server; they do not start separate servers:
- Scratchpad tools expose project-scoped Markdown scratchpads. Switch: Enabled in MCP in Settings > Features > Scratchpads.
- Todo tools expose project-scoped todos, blockers, locks, tags, and comments. Switch: Enabled in MCP in Settings > Features > Todos.
- Timer tools schedule user turns for Solo-managed agent processes. Switch: Timers in Settings > Agents > Timers.
- Key-value tools expose project-scoped JSON storage. Switch: Key-value tools in Settings > Agents > Key-value.
- Prompt template tools expose Solo prompt templates for listing, editing, and export. Switch: Prompt template MCP tools in Settings > Features > Prompt templates.
Settings > Integrations > MCP summarizes these groups, shows whether each is on, and links to its page with Edit.
Scratchpads, todos, and timers inherit MCP server enablement until an explicit setting is saved. Key-value and prompt template tools default off until enabled.
Turned-off features
Todos, Scratchpads, and Prompt templates also each have a feature switch at the top of their page in Settings > Features. Turning a feature off hides it throughout Solo and removes its MCP tools, plus its MCP resources for todos and scratchpads, even when its MCP switch is on. Its data is kept.
Calls to a hidden tool fail with a message that names the switch to turn back on:
- Feature off: "Todos are turned off in Solo. Turn them on in Settings > Todos."
- Only the MCP switch off: "Todo MCP tools are turned off. Turn them on in Settings > Todos."
Timer and key-value tools have only their MCP switch, so their message points to Settings > Agents > Timers or Settings > Agents > Key-value.
The same feature switches apply outside MCP. While Todos or Scratchpads are off, the local HTTP API refuses their endpoints with 403 forbidden, and the solo CLI prints the same message and exits with code 77.
Input validation
Many tools, including every tool that creates agents, todos, scratchpads, or timers, reject parameters they don't recognize instead of ignoring them. For example, todo_create rejects description and points you to body. Check a tool's input schema for its accepted fields.
Prompts and resources
Besides tools, the server exposes built-in MCP prompts (orchestration playbooks) and readable MCP resources for scratchpads and todos. See MCP prompts and resources.
Scope and identity
Most tools operate on the effective project scope. A client can select that scope with select_project, or Solo can infer it from the MCP session and the bound Solo process.
Agents launched by Solo are normally identified automatically. If auto-identification fails, identify_session lets a client assert its own SOLO_PROCESS_ID, and clients outside Solo can register as external actors. Use whoami to inspect the caller identity, effective project, and process association. See Agent and terminal tools.