What is the key difference between Cosmos MCP and Ratary?

Cosmos MCP belongs to the Knowledge & Memory category with local stdio execution, while Ratary belongs to the Knowledge & Memory category with local stdio execution.

How do I install Cosmos MCP or Ratary in Claude Desktop or Cursor?

Copy the mcpServers JSON configuration snippet provided on this page into your claude_desktop_config.json or ~/.cursor/mcp.json file and restart your AI client.

Are Cosmos MCP and Ratary free or paid?

Cosmos MCP operates under a Free / Open Source model (API Key required). Ratary operates under a Free / Open Source model (API Key required).

Which MCP server has more tools and community activity?

Cosmos MCP lists 6 tools with 3 views and 3 GitHub stars. Ratary lists 6 tools with 3 views and 1 GitHub stars.

Can I use both Cosmos MCP and Ratary together in the same MCP host?

Yes! MCP hosts like Claude Desktop, Cursor, Windsurf, Cline, and VS Code support configuring multiple servers under the mcpServers object simultaneously.

Side-by-Side Model Context Protocol Comparison

Cosmos MCP vs Ratary

In-depth architectural comparison of the Cosmos MCP and Ratary MCP servers. Compare execution transports, security boundaries, tool capabilities, quality scores, and ready-to-paste client installation snippets for Claude, Cursor, Windsurf, and VS Code.

At a Glance & Executive Verdict

Cosmos MCP

Knowledge & Memory · Local stdio

Quality: 56/100 (Good) | Auth: API Key required

Ratary

Knowledge & Memory · Local stdio

Quality: 49/100 (Fair) | Auth: API Key required

Verdict Summary: Choose Cosmos MCP if you need specialized Knowledge & Memory tools running via a local process. Choose Ratary if your workspace requires Knowledge & Memory integration with local subprocess execution. Both servers can be configured concurrently in your client's mcpServers manifest.

Which MCP Server Should You Choose?

Choose Cosmos MCP when:

You need dedicated capabilities in the Knowledge & Memory domain.
You prefer local stdio subprocess transport architecture.
Your security boundary fits: API Key required (Free / Open Source).
You have access to required keys: COSMOS_TOKEN.
Primary tools included: Shared account-keyed personal knowledge graph, Eleven MCP read and write tools, Portable .polarity graph export.

Explore Cosmos MCP Details

Choose Ratary when:

You need dedicated capabilities in the Knowledge & Memory domain.
You prefer local stdio subprocess transport architecture.
Your security boundary fits: API Key required (Free / Open Source).
You have access to required keys: AUTH_SECRET, DATABASE_URL, SQL_PROVIDER, RATARY_BASE_URL, RATARY_API_KEY.

Feature & Specification Comparison

Specification	Cosmos MCP teampolarity Knowledge & Memory	Ratary ontorata Knowledge & Memory
Summary	Personal knowledge graph shared across MCP clients. Account-keyed and portable as a .polarity file, with sources for iMessage, browser history, calendar, Claude Desktop transcripts, shell history, Notion, and Obsidian. npx -y @polarity-lab/cosmos-mcp	Persistent coding memory for AI assistants — hybrid search, knowledge graph, token-efficient context. MCP stdio (28 tools), npm @ratary/mcp-server, optional remote Streamable HTTP. Self-host D1, Postgres, MariaDB, or Docker.
Category & Scope

Tools & Capabilities Breakdown

Cosmos MCP Tools (6)

Shared account-keyed personal knowledge graph

Eleven MCP read and write tools

Portable .polarity graph export

Incremental iMessage and shell-history synchronization

Claude Code transcript synchronization

Notion and Obsidian source connections

Ratary Tools (6)

Persistent versioned memory

Ready-to-Paste Client Configurations

Paste either (or both) of these JSON server blocks into your client config file (e.g. claude_desktop_config.json or ~/.cursor/mcp.json).

Cosmos MCP Configuration

mcpServers (Claude Desktop / Cursor)

{
  "mcpServers": {
    "teampolarity-cosmos-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@polarity-lab/cosmos-mcp"
      ],
      "env": {
        "COSMOS_TOKEN": "YOUR_COSMOS_TOKEN_HERE"
      }
    }
  }
}

Ratary Configuration

mcpServers (Claude Desktop / Cursor)

{
  "mcpServers": {
    "ontorata-ratary": {
      "command": "npx",
      "args": [
        "-y",
        "@ratary/mcp-server@1.1.3"
      ],
      "env": {
        "AUTH_SECRET": "YOUR_AUTH_SECRET_HERE",
        "DATABASE_URL": "YOUR_DATABASE_URL_HERE",
        "SQL_PROVIDER": "YOUR_SQL_PROVIDER_HERE",
        "RATARY_BASE_URL": "YOUR_RATARY_BASE_URL_HERE",
        "RATARY_API_KEY": "YOUR_RATARY_API_KEY_HERE"
      }
    }
  }
}

Frequently Asked Questions

Cosmos MCP is categorized under Knowledge & Memory and uses a local stdio subprocess. In contrast, Ratary belongs to Knowledge & Memory using local stdio subprocess. Select Cosmos MCP when you need capabilities focused on knowledge & memory and Ratary when you require tools for knowledge & memory.

More alternatives to Cosmos MCP More alternatives to Ratary Knowledge & Memory category hub Canonical compare URL