Paperclip MCP

Complete, schema-driven Model Context Protocol access to the Paperclip API.

Paperclip MCP turns the supplied paperclip-openapi.json contract into typed MCP tools without maintaining a second, drifting interface registry. It exposes all 590 documented operations over stdio or authenticated Streamable HTTP, handles Paperclip deployments both with bearer authentication and in tokenless local_mode, and preserves the path, query, body, and authorization boundaries described by the source document.

What it provides

• One direct, schema-validated pc_* MCP tool for every OpenAPI method/path operation.

• Bounded paperclip_list_operations discovery and paperclip_call_operation dispatch by stable METHOD /path/{template} keys.

• Correct OpenAPI 3.0 nullable and exclusive-bound translation, path escaping, and query array serialization.

• JSON, text, JSONL, SSE transcript, and base64 binary responses behind one result envelope.

• Separate inbound MCP and outbound Paperclip bearer credentials; inbound credentials are never forwarded upstream.

• Optional upstream authentication: omit the Paperclip token for local_mode, or configure a board/agent bearer token when Paperclip requires authentication.

• Loopback-bound, non-root, read-only, capability-free Docker deployment with secret mounts, health/readiness probes, and resource limits.

Related MCP server: mcp-cli-catalog

Architecture

flowchart LR
    Client[MCP client] -->|stdio or HTTP Bearer A| Gateway[Paperclip MCP]
    Spec[paperclip-openapi.json] -->|590 validated operations| Gateway
    Gateway -->|No auth in local_mode| Local[Paperclip local_mode]
    Gateway -->|Bearer B when configured| Auth[Authenticated Paperclip]

Bearer A protects this service's HTTP endpoint. Bearer B belongs to Paperclip. They must be different, and neither is accepted as MCP tool input.

Quick start

Python 3.12 is required.

scripts/bootstrap.sh
export PAPERCLIP_BASE_URL=http://127.0.0.1:3100

For Paperclip local_mode, do not set PAPERCLIP_API_TOKEN:

.venv/bin/paperclip-mcp stdio

For a Paperclip instance that requires board or agent authentication:

export PAPERCLIP_API_TOKEN='paperclip-issued-token'
.venv/bin/paperclip-mcp stdio

The credential type determines which board-only, instance-admin, or agent-capable operations Paperclip will authorize. The MCP does not elevate upstream permissions.

Streamable HTTP

Create a gateway-only token and start the service:

.venv/bin/paperclip-mcp token --output secrets/mcp_token
export PAPERCLIP_MCP_TOKEN_FILE="$PWD/secrets/mcp_token"
.venv/bin/paperclip-mcp http

Connect an MCP client to http://127.0.0.1:8000/mcp with:

Authorization: Bearer <contents of secrets/mcp_token>

GET /healthz checks only the gateway. GET /readyz performs the public Paperclip health request and therefore works in both upstream authentication modes. On loopback, the inbound MCP token may be omitted for local development. Non-loopback binds fail closed unless it is configured.

Docker

Generate the inbound token file:

.venv/bin/paperclip-mcp token --output secrets/mcp_token
export PAPERCLIP_BASE_URL=http://host.docker.internal:3100
docker compose up --build -d

That starts against Paperclip local_mode with no upstream authorization header. For an authenticated Paperclip deployment, add the secret-only overlay:

install -m 600 /secure/path/paperclip-api-token secrets/paperclip_api_token
docker compose -f compose.yaml -f compose.auth.yaml up --build -d

The host port stays on 127.0.0.1. If Paperclip is another Compose service, place both on an appropriate user-defined network and set PAPERCLIP_BASE_URL to its service URL; do not use 127.0.0.1 inside this container to refer to the host.

Tool input and output

Direct tools group URL values so names cannot collide:

{
  "path": {"companyId": "company-123"},
  "query": {"limit": 25},
  "body": {"title": "Example"}
}

The source contract currently omits request schemas for three upload routes. Their tools provide a marked compatibility input:

{
  "path": {"companyId": "company-123"},
  "multipart": {
    "file": {
      "filename": "diagram.png",
      "media_type": "image/png",
      "data_base64": "iVBORw0KGgo..."
    }
  }
}

Success results use {status_code, content_type, headers, body, encoding}. Non-success responses become MCP tool errors. See the generated reference and MCP client guide.

Documentation

• Architecture and contract generation

• MCP client configuration

• Operations and credential rotation

• Security model

• Testing and evidence boundaries

• Generated tool reference

Development

scripts/ci-bootstrap.sh
scripts/validate.sh

Validation checks formatting, lint, strict typing, compilation, the full test suite with branch coverage, generated documentation, distributions, and both Compose modes. Live Paperclip acceptance and built-container security checks are separate operator-run gates; mocked upstream tests do not constitute live service evidence.