Claude Code

Claude Code starts stdio MCP servers from its configuration. stretto init --host claude-code prints the command that adds your server to it, behind stretto-proxy.

Add the server

stretto init --host claude-code --domain notes \
  -- npx -y @modelcontextprotocol/server-filesystem /home/me/notes

It prints a claude mcp add command, on one line (wrapped here). Run it in the project where you use Claude Code:

claude mcp add notes -- stretto-proxy \
  --record ~/.stretto/logs/notes --domain notes \
  -- npx -y @modelcontextprotocol/server-filesystem /home/me/notes

Everything after the first -- is the server's command: stretto-proxy and its arguments, then, after the proxy's own --, the real server's command. By default the server is added for you in the current project. With claude mcp add --scope user, it applies to every project; with --scope project, it is written to the project's .mcp.json, to share.

After the command, init prints the next steps, from learning a flow to serving it: the quick start follows them.

Or write the project's .mcp.json

stretto init --host claude-code --domain notes --write .mcp.json \
  -- npx -y @modelcontextprotocol/server-filesystem /home/me/notes

It writes:

{
  "mcpServers": {
    "notes": {
      "command": "stretto-proxy",
      "args": ["--record", "~/.stretto/logs/notes", "--domain", "notes",
               "--", "npx", "-y", "@modelcontextprotocol/server-filesystem",
               "/home/me/notes"]
    }
  }
}

A .mcp.json at the project's root configures servers for everyone working in it, and Claude Code asks each person to approve a project's servers before it starts them. --write leaves an existing .mcp.json alone unless you add --force, which replaces the whole file, with any other servers in it. To add the server to a file that has others, run the printed claude mcp add command with --scope project instead.

Check it

claude mcp list

In a session, /mcp shows each server's status. After the first session, the proxy's log is in ~/.stretto/logs/notes/.

Serve a flow

Once you have learned and reviewed a flow, run init again with it:

stretto init --host claude-code --domain notes \
  --flow ~/.stretto/notes.flow.json \
  -- npx -y @modelcontextprotocol/server-filesystem /home/me/notes

claude mcp add notes -- stretto-proxy \
  --record ~/.stretto/logs/notes --domain notes \
  --flow /home/me/.stretto/notes.flow.json --flow-decider reach \
  -- npx -y @modelcontextprotocol/server-filesystem /home/me/notes

The server is already configured under that name, so remove it first (claude mcp remove notes), then run the new command and restart Claude Code. Claude Code then sees each of the flow's lookups inside the result of the call it made, under --- Also looked up automatically ... ---.

• Add --shadow to init to see what the flow would do before it acts (shadow mode).
• A flow learned with --habit-only has no arbiter, so init serves it with reach, which asks no model and needs no key (deciders).

Notes

• Naming the model. The proxy cannot see which model drives Claude Code. Add --agent-model <model> to the proxy's arguments, before its --, to write it into the log's header.
• The live research ran here. The pilots ran GLM-5.3 in Claude Code, with τ²-bench's tools served over MCP behind stretto-proxy (the paper, §3).
• Several servers. Wrap each in its own proxy, with its own --domain; init gives each its own --record directory.

Any MCP host has what applies to every host: paths, credentials and exit codes.