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streamlit-mcp

Serve any Streamlit app as an MCP server. Agents introspect your app's widgets, set values, click buttons, and read the rendered output and session_state — natively, over MCP, with no browser automation.

pip install streamlit-mcp          # or run with no install via: uvx streamlit-mcp ...

# serve an app over MCP (stdio for local clients)
streamlit-mcp serve app.py
# ...or HTTP/SSE on loopback for local networked agents
streamlit-mcp serve app.py --transport http --port 8000

# drive it yourself from the terminal (same engine the agent uses)
streamlit-mcp inspect app.py
streamlit-mcp call app.py --set "Name=agent" --click "Save" --read

Streamlit has no callback graph — it reruns the whole script per interaction — so streamlit-mcp drives the app headlessly through Streamlit's own test runtime (streamlit.testing.v1.AppTest) and returns the semantic element tree, not pixels. Gradio and Dash already shipped native app-as-MCP; this fills the Streamlit gap.

See it

A normal Streamlit app — the kind a human opens in a browser:

A Streamlit signup form running in a browser

The same app, driven by an agent over MCP — inspect to see the widgets, call to set values, click a button, and read the rendered result. No browser, no pixels:

The streamlit-mcp CLI introspecting and driving the app

…and a human can watch the agent work live in their browser — no refresh, no browser automation (how):

A browser updating live as an agent edits the app over MCP

The agent can even add components and rearrange the layout by driving state the app branches on (how).

Why it's nice

  • No browser, no pixels. Agents get a structured element tree and session_state, not screenshots.
  • Human ↔ agent parity. Everything an agent can do over MCP, a human can do via the CLI — both call the same engine, and the guardrails apply identically.
  • Atomic, honest writes. An invalid option or out-of-range value is rejected up front with a clear error; a failed set_widget never poisons a long-lived session or silently mutates state.
  • Enforced auth. A --bearer-token is actually required on HTTP/SSE (401 otherwise).

Next

  • Usage — MCP-client config, the tools, custom semantic tools, and the CLI.
  • Security — the trust model, bearer auth, and current limitations.
  • Changelog.