Houston Beta
Houston docs

MCP servers

Connect Model Context Protocol servers in Settings: a local stdio process, or a remote HTTP (streamable) or SSE endpoint.

  • Naming. Their tools are offered to the agent as mcp__<id>__<tool>.
  • Approval. MCP tools always require approval.
  • Many tools, loaded lazily. With more than 15 MCP tools connected, Houston loads their schemas on demand: they join the find_tools catalog (see "Tools loaded on demand" under "Context, worktrees, and history"), and the agent pulls in only the tool definitions it needs instead of sending every schema on every request.

Signing in

Remote servers take custom headers (such as a static Authorization: Bearer token), or OAuth for servers that need a sign-in:

  • Sign in: click Sign in (OAuth) on the server in Settings (desktop), or run /mcp login <n> (terminal). Houston discovers the server's authorization server, registers itself as an OAuth client automatically, and opens the browser to authorize.
  • Tokens are stored encrypted, sent as the bearer on every connection, and refreshed automatically when they expire.
  • Sign out (or /mcp logout <n>) forgets them.
  • An explicit Authorization header, when set, takes precedence over OAuth tokens.

Local (stdio) servers

  • Give them a working directory and environment variables in Settings, or through the /mcp add prompts.
  • The spawned process gets a base environment with credentials stripped, so a token the server needs must be listed explicitly.
  • Environment values are treated as secrets and stored encrypted, like header values.

Resources and prompts

When a server exposes MCP resources or prompt templates, the agent gets meta-tools to discover and fetch them: mcp_list_resources / mcp_read_resource and mcp_list_prompts / mcp_get_prompt.

Houston also:

  • honors list_changed notifications, so tools, resources, and prompts refresh live
  • keeps long tool calls alive while the server reports progress
  • caps any single MCP result, so a runaway server can't flood the context window

Checking a server

  • /mcp tools <n> lists exactly which tools a server exposes. A count tells you it works; the names tell you what you just handed the agent.
  • /mcp in the terminal and the Settings panel show each server's live status: connected with a tool count, needs sign-in, or the connection error.

Server questions (elicitation)

A server can ask for input in the middle of a tool call, such as a region, a project name, or a confirmation.

  • Desktop app: a small form naming the server, with typed fields and Submit / Decline. Your answer goes to that MCP server, not to the model.
  • Terminal: an inline prompt (decline with n).
  • Headless or background runs: declined automatically, so nothing hangs waiting for a user who isn't there, and the server proceeds along its no-answer path.
  • Stopping the run cancels any open request.

Protocol versions

Houston speaks MCP protocol versions 2025-06-18, 2025-03-26, and 2024-11-05, and asks for the newest when it connects.

  • A server that answers with an older supported version still works, but server questions need 2025-06-18: an older server's requests for input are declined.
  • A server that only speaks a version outside that list fails to connect, and its status names the version it asked for.