pwpush-mcp

A Model Context Protocol (MCP) server for Password Pusher — create and manage self-destructing secret links from any MCP-compatible client (Claude Desktop, Claude Code, etc.).

Why a "preview but never retrieve" design?

Retrieving a push consumes a view and is irreversible. To keep secrets safe, this server never retrieves a push payload. It can create pushes and hand back the shareable URL, preview that URL (without consuming a view), and manage the lifecycle (expire, audit, list). The secret is only ever read by the human who opens the link.

Related MCP server: rustypaste-mcp-server

Tools

* The bearer token is sent whenever PWPUSH_API_TOKEN is set. Whether it is required depends on the instance: some allow anonymous push creation, preview, and expiry (for pushes created with deletable_by_viewer). Listing and audit are always account-scoped and need a token.

Defaults

New pushes expire after 1 view or 7 days (whichever comes first), with a retrieval step enabled. Override per call via expire_after_views and duration.

File pushes

Attach one or more local files by passing file_paths; kind is forced to file and the upload is sent as multipart. payload is optional in that case.

Prompts

User-controlled templates (slash-command style in clients that support MCP prompts). A prompt renders a message that guides the assistant to call the matching tool — it never touches the API itself.

Prompts follow the same gating as tools: PWPUSH_READ_ONLY=true hides the write prompts (create_push, expire_push), and PWPUSH_ENABLED_TOOLS filters prompts by name too — a prompt is offered only when its tool is.

Configuration

Set via environment variables — the API token is never a tool argument:

Security & multi-tenant

• PWPUSH_READ_ONLY=true strips the write tools entirely — only preview_push, get_push_audit, list_* and get_version remain. expire_push is the one destructive tool (destructiveHint), so clients can warn on it.

• PWPUSH_ENABLED_TOOLS narrows the exposed surface to an allowlist of fnmatch globs, e.g. expose only listing/preview to an auditor.

• PWPUSH_AUDIT_LOG (on by default) writes one JSON line per write call to the pwpush_mcp.audit logger on stderr — ship it to Loki/CloudWatch/journald via your runtime. Secrets (payload, passphrase, note, name, file contents, token) are redacted; name is hashed in the audit target for grep-ability. The token is also redacted from Config reprs and error text.

• PWPUSH_FILE_ROOT gates file pushes. File uploads are disabled by default because their bytes become retrievable via the returned share URL — an exfiltration vector for an over-eager or malicious client. Set it to a directory to enable uploads from that subtree only; ~ expansion and symlink resolution are applied before the containment check, so ../ traversal and symlink escapes are rejected.

HTTP transport (--listen) is sensitive. The server may hold PWPUSH_API_TOKEN and exposes account-scoped tools. The transport has no TLS of its own, so:

• it binds 127.0.0.1 by default — only bind a public interface behind a TLS + auth reverse proxy;

• it requires MCP_HTTP_TOKEN (clients send Authorization: Bearer <token>) and refuses to start without it, unless you set MCP_HTTP_ALLOW_UNAUTHENTICATED=true;

• it validates the Host header (MCP_HTTP_ALLOWED_HOSTS) to block DNS-rebinding from a browser.

stdio mode is unaffected by all of the above.

Multi-tenant (per-client credentials)

By default the HTTP server uses one shared identity (PWPUSH_API_TOKEN). Set PWPUSH_PER_REQUEST_CREDENTIALS=true to instead let each client supply its own pwpush credentials, so one hosted server serves many accounts:

• the client sends X-Pwpush-Token (and X-Pwpush-Email for v1 instances) as HTTP headers; the server builds a per-request, per-tenant client from them;

• credentials ride the transport, never a tool argument — they are never seen by the language model and are kept out of logs (the header is scrubbed);

• only the credentials are per-request. base_url, read_only, enabled_tools and file_root stay operator-controlled, so a tenant can neither redirect the instance nor widen its own permissions;

• if a request sends no X-Pwpush-Token, it falls back to the env token (so you can run a pure multi-tenant server with no PWPUSH_API_TOKEN at all — account-scoped calls then simply require the header).

Credentials in headers travel in clear text: serve only behind TLS. MCP_HTTP_TOKEN (transport gate) and X-Pwpush-Token (tenant identity) are independent — keep both for a shared hosted deployment.

Example client config (MCP client that supports HTTP headers):

{
  "mcpServers": {
    "pwpush": {
      "url": "https://pwpush-mcp.example.com/mcp",
      "headers": {
        "Authorization": "Bearer <MCP_HTTP_TOKEN>",
        "X-Pwpush-Token": "<this-client's-pwpush-token>",
        "X-Pwpush-Email": "<this-client's-email, v1 only>"
      }
    }
  }
}

API v1 / v2

The server speaks both the modern v2 API (pwpush.com, eu.pwpush.com, recent self-hosted) and the legacy v1 API (older self-hosted instances). It auto-detects which one the instance exposes. Note for v1: expiry is day-granular, so sub-day duration values round up to one day, and file/URL pushes are only available if the instance enables them.

Both paths are exercised end-to-end: v1 against a live legacy instance, v2 against pwpush.com (API 2.1). v2 calls target the .json endpoints deliberately — the suffix-less paths issue a cross-host redirect, so they are avoided to keep the payload from leaking to another host.

duration accepts a human label (15m, 30m, 45m, 1h, 6h, 12h, 1d, 2d, 3d, 4d, 5d, 6d, 1w, 2w, 3w, 1mo, 2mo, 3mo) or the raw enum index 0–17.

Install & run

Published as pwpush-mcp on PyPI and ghcr.io/k9fr4n/pwpush-mcp on GHCR, produced by the release workflow on each version tag (latest: v0.5.0).

With uv (recommended):

uvx pwpush-mcp

Or with pipx:

pipx run pwpush-mcp

From source:

pip install -e ".[dev]"
python -m pwpush_mcp

Transports

stdio is the default (Claude Desktop / Claude Code / Docker MCP Gateway). To expose the server over the network as Streamable HTTP (single /mcp endpoint, MCP spec revision 2025-03-26+ — the legacy HTTP+SSE transport it replaces is deprecated):

# Requires MCP_HTTP_TOKEN; binds 127.0.0.1:8000 by default, endpoint at /mcp.
MCP_HTTP_TOKEN=$(openssl rand -hex 32) pwpush-mcp --listen 8000
# Clients then send:  Authorization: Bearer <MCP_HTTP_TOKEN>  to http://127.0.0.1:8000/mcp

Docker

docker run --rm -i \
  -e PWPUSH_BASE_URL="https://pwpush.com" \
  -e PWPUSH_API_TOKEN="your-token-here" \
  ghcr.io/k9fr4n/pwpush-mcp:latest          # stdio (default)

HTTP mode via compose.yml (override the entrypoint with --listen):

cp .env.example .env && $EDITOR .env
docker compose up        # serves Streamable HTTP on http://localhost:8000/mcp

For v1 (legacy self-hosted) instances also pass -e PWPUSH_API_EMAIL=....

Docker MCP Gateway

The image ships the io.docker.server.metadata label and a catalog entry so the Docker MCP Gateway can spawn it natively. See catalog/readme.md:

docker mcp catalog create pwpush-private
docker mcp catalog add  pwpush-private pwpush-mcp ./catalog/server.yaml
docker mcp server  enable pwpush-mcp
docker mcp gateway run    --catalog pwpush-private

Client configuration

Claude Desktop / Claude Code (mcp config)

{
  "mcpServers": {
    "pwpush": {
      "command": "uvx",
      "args": ["pwpush-mcp"],
      "env": {
        "PWPUSH_API_TOKEN": "your-token-here",
        "PWPUSH_BASE_URL": "https://eu.pwpush.com"
      }
    }
  }
}

Development

pip install -e ".[dev]"
ruff check src tests && ruff format --check src tests
mypy src
pytest -q --cov=pwpush_mcp --cov-fail-under=80

See CONTRIBUTING.md for the tool/env-var checklists and the release process, and CHANGELOG.md / UPGRADING.md for version history.

License

MIT — see LICENSE.