Calypso MCP Server

Calypso Multimodal RAG MCP Server

The easiest hosted multimodal RAG MCP server for Claude Desktop, Cursor, and agent workflows.

One npx command. Gemini File Search-powered. Handles PDFs, screenshots, charts, diagrams, and images natively with verifiable citations.

The easiest way to add hosted multimodal RAG to Claude, Cursor, Windsurf, and custom agents.

• Super simple setup: npx -y @calypsohq/multimodal-rag-mcp-server --api-key sk-your-key-here
• True multimodal RAG: handles text and visuals natively through Gemini File Search
• Upload and query: dedicated tools for durable knowledge files and batch uploads
• Multi-turn conversations: context-aware answers with /new reset
• Discoverable workflows: resources and prompts for safe RAG, upload, and ingestion flows

GitHub | Docs | Smithery | Official MCP Registry

Tags: multimodal-rag, easiest-mcp-rag, gemini-rag, hosted-rag-mcp, mcp-server

Instead of wiring each agent or workflow to a one-off document search stack, use this MCP as the agent-facing entry point to one reusable answer layer: upload source material once, retrieve across text and visual content, and return answers with evidence users can verify.

Quick Start (Easiest)

# One-liner with npx
npx -y @calypsohq/multimodal-rag-mcp-server --api-key "sk-your-key-here"

Or with environment variables:

CALYPSO_API_KEY="sk-..." npx -y @calypsohq/multimodal-rag-mcp-server

Then add the same command to Claude Desktop, Cursor, or Smithery using the configuration examples below.

Why Choose Calypso

Calypso is built for teams that want the easiest hosted multimodal RAG MCP server: no local vector stack, no Docker compose, and no custom OCR or image-processing pipeline before agents can ask grounded questions.

Start here if you want the easiest hosted multimodal RAG MCP server.

What you get

• Production multimodal RAG agent with multi-turn memory
• Built-in upload tools for single files and batch knowledge uploads
• Automatic discovery of your team's RAG variants and knowledge buckets
• Verifiable citations with source references and retrieval metadata
• Read-only resources and reusable prompts for safe workflows

Why Multimodal-First RAG

Most company knowledge is not only text. The answer often lives across a setup screenshot, a PDF table, a product diagram, a help-center page, or a chart inside a report. Calypso packages that full knowledge surface into a single retrieval layer so agents can ask grounded questions without guessing from generic model memory.

• Search the formats users actually rely on: documentation, PDFs, screenshots, charts, diagrams, product images, support articles, manuals, policies, FAQs, and reports.
• Ground answers before the model writes: Gemini File Search retrieves relevant text and visual context first, then the RAG agent answers from that source material.
• Show the evidence trail: responses can include source references, page-aware grounding, and retrieval metadata so people can verify before they trust.
• Scope retrieval with metadata: use workspace, team, customer, language, file type, status, or other metadata to keep answers relevant without duplicating knowledge bases.
• Reuse the same knowledge layer everywhere: connect Cursor, Claude Desktop, AI agents, n8n workflows, product UI, support flows, and website experiences to the same source-backed layer.

In practice, this means your agent can answer questions like:

• "Explain this setup screenshot and the attached policy PDF. What should the support rep do next?"
• "What does this onboarding PDF say about approval rules?"
• "Why is this setup screen failing?"
• "Compare the pricing chart with our plan documentation and recommend the right tier."
• "Summarize the policy that applies to this support ticket."
• "Which product plan fits this customer based on our pricing docs?"
• "Compare the diagrammed ingestion flow with the retrieval flow."

What this MCP does

With calypso-rag-agent you can:

• Ask grounded questions against the configured Calypso knowledge base
• Select any discovered team RAG variant with the optional model argument
• Continue a multi-turn conversation via the native /v1/responses conversation model
• Reset the conversation context with /new
• Use the same OpenAI-compatible Responses endpoint that serves calypso-rag-agent
• Discover built-in resources and prompts for the supported Calypso workflows

Requirements

• Node.js 18+
• The server uses Web Fetch API primitives (fetch, Headers, Request, Response, FormData, Blob, and File) for API calls and SDK compatibility. The package bootstraps missing globals at startup for MCP runtimes that expose only part of the Node 18+ Web API surface.
• A Calypso API endpoint that exposes:
  • POST /v1/responses
  • GET /v1/rag-agent/models
  • GET /v1/knowledge/buckets
  • POST /v1/knowledge/files/upload-session
  • POST /v1/knowledge/files/upload-session/{session_id}/finalize
  • POST /v1/knowledge/files:batch/upload-session
  • POST /v1/knowledge/files:batch/upload-session/{batch_id}/finalize
  • GET /v1/knowledge/batches/{batch_id}
• A Calypso API key (sk-...)

Configuration

Environment variables:

• CALYPSO_API_KEY (required)
• CALYPSO_API_BASE_URL (optional, default https://api.calypso.so/v1)

CLI flags:

• --api-key
• --api-base-url

Configuration precedence:

1. CLI flags / Smithery-provided command arguments
2. Environment variables
3. Default base URL (https://api.calypso.so/v1)

Run with npx

npx -y @calypsohq/multimodal-rag-mcp-server --api-key "sk-..."

Run with environment variables

env CALYPSO_API_KEY="sk-..." CALYPSO_API_BASE_URL="https://api.calypso.so/v1" npx -y @calypsohq/multimodal-rag-mcp-server

Configure in Cursor

Add a new MCP server (command type) like:

npx -y @calypsohq/multimodal-rag-mcp-server --api-key sk-... --api-base-url https://api.calypso.so/v1

Configure in Claude Desktop

1. Open Claude Desktop MCP config

In Claude Desktop:

Claude -> Settings -> Developer -> Edit Config

On macOS, the file is usually:

~/Library/Application Support/Claude/claude_desktop_config.json

Claude Desktop uses claude_desktop_config.json for desktop MCP servers. Claude Code uses separate config locations such as ~/.claude.json or project-level .mcp.json.

2. Add the Calypso MCP server

Paste this into claude_desktop_config.json:

{
  "mcpServers": {
    "Calypso Multimodal RAG": {
      "command": "npx",
      "args": [
        "-y",
        "@calypsohq/multimodal-rag-mcp-server"
      ],
      "env": {
        "CALYPSO_API_KEY": "sk-your-calypso-api-key",
        "CALYPSO_API_BASE_URL": "https://api.calypso.so/v1"
      }
    }
  }
}

Replace:

• sk-your-calypso-api-key

with your real Calypso API key.

3. Restart Claude Desktop fully

Fully quit Claude Desktop, then reopen it.

Do not only close the window. On macOS:

Cmd + Q

After restart, the MCP should appear in Claude with these tools available:

• calypso-rag-agent
• calypso-list-knowledge-buckets
• calypso-upload-knowledge-file
• calypso-upload-knowledge-files-batch

Optional: Save Claude Artifacts To Your Mac

Calypso provides hosted multimodal RAG tools. It does not write generated reports, summaries, CSVs, JSON files, or web-search artifacts directly to your local computer.

To let Claude Desktop save generated files locally, add the standard filesystem MCP server alongside Calypso and restrict it to a dedicated safe folder.

Create the folder first:

mkdir -p ~/Claude

Then add both servers to claude_desktop_config.json:

{
  "mcpServers": {
    "Calypso Multimodal RAG": {
      "command": "npx",
      "args": [
        "-y",
        "@calypsohq/multimodal-rag-mcp-server"
      ],
      "env": {
        "CALYPSO_API_KEY": "sk-your-calypso-api-key",
        "CALYPSO_API_BASE_URL": "https://api.calypso.so/v1"
      }
    },
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/yourname/Claude"
      ]
    }
  }
}

Fully quit and reopen Claude Desktop after changing the config.

Example prompt:

Use Calypso for the grounded RAG answer, then save the final report as /Users/yourname/Claude/report.md using the filesystem tool.

For safety, only grant filesystem access to a dedicated folder such as ~/Claude, not your whole home directory.

Smithery

The server is available on Smithery and launches through the same npx package path used by desktop clients.

Smithery user config:

• calypsoApiKey (required)
• calypsoApiBaseUrl (optional, defaults to https://api.calypso.so/v1)

The Smithery launch path is equivalent to:

npx -y @calypsohq/multimodal-rag-mcp-server --api-key sk-... --api-base-url https://api.calypso.so/v1

Use calypsoApiBaseUrl only when targeting a self-hosted Calypso-compatible deployment. The cloud default does not need an override.

Troubleshooting

• Missing API key: provide --api-key or CALYPSO_API_KEY
• Wrong API host: make sure --api-base-url / CALYPSO_API_BASE_URL ends in /v1
• Self-hosted deployment: only override the base URL if you are not using https://api.calypso.so/v1
• Smithery launch mismatch: use the packaged npx -y @calypsohq/multimodal-rag-mcp-server path instead of running node dist/index.js from a fresh clone
• FormData is not defined or Headers is not defined: upgrade to the latest package. The MCP server bootstraps missing Web Fetch API globals before upload tools run.
• ENOENT for /mnt/user-data/uploads/...: that path belongs to a hosted agent or attachment sandbox, not necessarily to the MCP server. Retry with contentBase64 instead of filePath.
• Local artifact saving: Calypso answers can be used with Claude Desktop's filesystem MCP server, but Claude must be explicitly asked to save the final output to an allowed local path.

Choosing filePath vs contentBase64

Use filePath for local MCP installs, including Claude Desktop and Cursor configs that launch this package with a local command such as:

npx -y @calypsohq/multimodal-rag-mcp-server

In that setup, the MCP server process runs on your machine and can read paths available to the same user account. Pass the local path directly; the server reads raw bytes and uploads them through the Calypso upload-session URL. You do not need to base64-encode local files.

Use contentBase64 for hosted or remote MCP clients, including Smithery-hosted servers, browser/cloud runtimes, generated in-memory content, and agent containers. In those environments, a path on your Mac or workstation is not readable by the MCP server process.

If a path starts with /mnt/user-data/uploads, /mnt/data, /mnt/attachments, or another hosted sandbox prefix, do not send it as filePath unless this MCP server is running in that same sandbox. Use contentBase64 or another inline byte source instead.

Available tools

calypso-rag-agent

Direct Calypso RAG agent access.

Notes:

• It does not auto-route to other personas or agents.
• It automatically discovers the API key's available calypso-rag-agent variants at startup.
• Use the optional model argument to choose a named variant such as calypso-rag-agent:pricing.
• Each model variant keeps its own MCP conversation chain, so switching variants does not continue the wrong thread.
• It uses POST /v1/responses instead of POST /v1/chat/completions.
• First turns create a named conversation, and follow-up turns chain with previous_response_id.
• Optional fileIds are supported for retrieval-scoped questions. New uploads should use the durable knowledge upload tools and wait for indexing before asking.
• Use /new as the prompt to reset the MCP conversation.

calypso-list-knowledge-buckets

Lists knowledge buckets for the team tied to the configured Calypso API key.

Notes:

• Uses GET /v1/knowledge/buckets.
• Does not accept team_id; Calypso derives team scope from the API key.
• Returns bucket ids, slugs, names, status, member counts, source counts, and bucket-store readiness.
• Defaults to active buckets only. Pass includeArchived: true when you need archived buckets for audits or cleanup.
• Use this before calypso-upload-knowledge-file or calypso-upload-knowledge-files-batch when you need to choose a destination bucket.
• calypso://rag-agent-models answers which buckets are bound to each RAG variant. calypso-list-knowledge-buckets answers which buckets exist for the API key's team.

Example:

{
  "includeArchived": false
}

calypso-upload-knowledge-file

Uploads a file into the durable bucket-backed knowledge store and indexing pipeline.

Notes:

• Uses POST /v1/knowledge/files/upload-session, uploads bytes directly to storage, then finalizes with POST /v1/knowledge/files/upload-session/{session_id}/finalize.
• Uploads use JSON session requests plus signed binary PUTs, not multipart form uploads.
• Returns knowledge-file and task metadata, not a chat attachment file_id.
• Requires one bucket destination via bucketIds, bucketSlugs, or bucket.
• Use filePath for local Claude Desktop/Cursor MCP installs where the server can read the path. Use contentBase64 for hosted or remote MCP clients that cannot read local paths.
• If an agent sees a path like /mnt/user-data/uploads/file.pdf, it should not send that as filePath; it should send the file bytes as contentBase64.
• Supports optional title, tags, metadata, and idempotencyKey.
• Route uploads into existing buckets with bucketIds or bucketSlugs, or use bucket as a single-slug shortcut.
• Pass createMissingBuckets: true with bucket slugs when you want Calypso to create missing destinations during upload.
• Can optionally wait until indexing reaches a ready state before returning.

Example:

{
  "filename": "handbook.pdf",
  "mimeType": "application/pdf",
  "filePath": "/Users/me/Documents/handbook.pdf",
  "bucket": "support-handbook",
  "createMissingBuckets": true,
  "waitForIndexing": true
}

calypso-upload-knowledge-files-batch

Uploads 1 to 100 files into the durable knowledge store in one request.

Notes:

• Uses POST /v1/knowledge/files:batch/upload-session, uploads each accepted item directly to storage, then finalizes with POST /v1/knowledge/files:batch/upload-session/{batch_id}/finalize.
• Uploads use JSON session requests plus signed binary PUTs, not multipart form uploads.
• Requires batchIdempotencyKey; Calypso uses it to derive the durable batch id for retries.
• Requires a shared bucket destination via bucketIds, bucketSlugs, or bucket, unless every item provides its own bucket destination.
• Supports shared bucketIds, bucketSlugs, bucket, and createMissingBuckets defaults, plus per-item overrides.
• Use per-item filePath for local Claude Desktop/Cursor MCP installs where the server can read each path. Use per-item contentBase64 for hosted or remote MCP clients that cannot read local paths.
• Generates Firestore-safe client_file_id values when clientFileId is omitted.
• accepted or queued means the upload is durable, not necessarily query-ready. Use waitForBatchReady: true to poll GET /v1/knowledge/batches/{batch_id}?include_items=true.
• Inspect per-item status, bucketSyncStatus, and bucketSync to distinguish indexed content from bucket-ready retrieval.

Example:

{
  "batchIdempotencyKey": "kb-seed-2026-06-04",
  "bucket": "support-handbook",
  "createMissingBuckets": true,
  "items": [
    {
      "filename": "faq.txt",
      "mimeType": "text/plain",
      "filePath": "/Users/me/Documents/faq.txt"
    }
  ],
  "waitForBatchReady": true
}

Available resources

calypso://server-info

Read-only server metadata, including package version, API base URL, transport, authentication model, and exposed capabilities.

calypso://rag-agent-models

Read-only runtime catalog of team-scoped calypso-rag-agent model variants discovered from the configured API key, including each variant's active buckets, bucket_ids, and missing_bucket_ids. If discovery is unavailable, this resource falls back to the base calypso-rag-agent.

calypso://knowledge-buckets

Read-only runtime list of knowledge buckets for the team tied to the configured API key. Use it to inspect bucket ids/slugs and bucket-store readiness before uploads.

calypso://workflows

A compact guide to the supported RAG and knowledge-file workflows.

calypso://security

Operational security notes for API keys, local file reads, uploads, and logging.

Available prompts

• calypso-knowledge-question: draft a grounded knowledge-base question for calypso-rag-agent
• calypso-knowledge-ingestion: prepare a durable knowledge-store upload and follow-up query
• calypso-reset-conversation: start a clean RAG thread with /new

Common workflows (copy/paste)

Knowledge retrieval

• Summarize a topic:
  • Summarize the knowledge base guidance for campaign approvals
• Ask for a specific answer:
  • What does our documentation say about indexing retries?
• Compare two concepts:
  • Compare file indexing with retrieval execution in the current architecture
• Start a fresh thread:
  • /new

Multi-turn follow-up

• Refine a previous answer:
  • Focus only on the ingestion path and ignore retrieval
• Ask for sources or justification:
  • Explain which documented components are involved and why

Knowledge-store file flow

• Discover buckets:
  • Call calypso-list-knowledge-buckets or read calypso://knowledge-buckets before choosing a destination
• Upload durable knowledge:
  • Call calypso-upload-knowledge-file with the file payload and optional title, tags, or metadata
  • Prefer filePath for local Claude Desktop/Cursor MCP installs; use contentBase64 for hosted or remote MCP clients that cannot read local paths
• Route knowledge into buckets:
  • Use bucket: "support-handbook" for one destination, bucketSlugs for multiple slug-based destinations, or bucketIds when you already have stable bucket ids
• Create bucket destinations on demand:
  • Add createMissingBuckets: true when using slug-based bucket assignment and the destination may not exist yet
• Wait for indexing:
  • Pass waitForIndexing: true if you want the tool to block until the knowledge file is indexed

Knowledge-store batch flow

• Upload many durable files:
  • Call calypso-upload-knowledge-files-batch with items, batchIdempotencyKey, and filePath per item for local MCP installs; use contentBase64 per item for hosted or remote MCP clients
• Route the batch into buckets:
  • Put shared bucket, bucketSlugs, bucketIds, or createMissingBuckets on the tool call, then override per item only when needed
• Wait for query readiness:
  • Use waitForBatchReady: true and inspect returned item status plus bucket sync fields before querying fresh content

Tips

• Start over: use /new to reset the MCP conversation (new conversation_id + cleared response chain).