SSyncDev

Plugin MCP Server

Circulara Observe MCP plugin - meters your AI agents' token spend and carbon, free tier.

Local serverstdio

What is the Plugin MCP server?

Circulara Observe MCP plugin - meters your AI agents' token spend and carbon, free tier. The plugin mcp server wraps that behind the Model Context Protocol, so an assistant can use it through 4 defined tools rather than through you.

What it actually does

Circulara Observe tier: per-tenant backend + MCP plugin. Sprints 1-4: WS0 (scaffold), WS6 (pricing registry), WS1 (MCP plugin), WS2 (auth + BYO keys + gateway), WS3 (telemetry pipeline: normalize -> re-price -> append; free-tier cap; OpenAI-format gateway for Cursor-class hosts), WS4 (meter compute: registry pricing, energy/CO2e ranges with confidence labels, per user/team/module/month report), WS5 (Observe dashboard + savings-potential report + monthly statement, server-rendered, Ledger Light brand tokens; seed a demo tenant with packages/backend/scripts/seed-demo.ts and open the printed /dashboard URL).

Its toolset

Everything the assistant can do here goes through one of these:

  • Humans — OIDC/SSO (RS256 vs org issuer JWKS; admin via circulara_role=admin claim)
  • Gateway — unknown credential 401; missing tenant key 503; per-seat attribution exact;
  • OIDC — wrong issuer rejected; dev tokens rejected outside dev mode; agent tokens expire
  • Package — What

Adding it to your client

Installation goes through your MCP client rather than a global install: point it at tsx on npm and it is fetched when the client starts. The copy-paste blocks for Claude Desktop, Claude Code and Cursor are further down this page.

Configuration

You will need 7 environment variables: CIRCULARA_BACKEND_URL, CIRCULARA_TENANT_ID, CIRCULARA_TOKEN, CIRCULARA_SEAT_ID, CIRCULARA_USER_ID, CIRCULARA_MASTER_KEY, CIRCULARA_AGENT_TOKEN_SECRET. The server will not start without them, which is usually why the tools fail to appear on a first run. Keep credentials in your client's env block or a secrets manager rather than in a file you might commit.

When to reach for it

Plenty of developer tooling servers cover similar ground. The differences that matter in practice are scope of access and how much setup stands between you and a working tool call. Plugin's toolset — Humans, Gateway, OIDC and 1 more — is a fair guide to whether it matches your workflow. It is maintained by ai.circulara; worth a glance at recent repository activity before you build anything load-bearing on it.

SyncDev reviews every entry in this directory against the project's own documentation before publishing, and revisits them as servers change.

Caveats

  • It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
  • Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
  • MCP clients confirm each tool call by default. Leave that on until you have watched what the plugin mcp server does with a few real requests.

Available tools

ToolWhat it does
HumansOIDC/SSO (RS256 vs org issuer JWKS; admin via circulara_role=admin claim).
Gatewayunknown credential 401; missing tenant key 503; per-seat attribution exact;
OIDCwrong issuer rejected; dev tokens rejected outside dev mode; agent tokens expire.
PackageWhat

How to install the Plugin MCP server

{
  "mcpServers": {
    "server-plugin": {
      "command": "npx",
      "args": ["-y", "tsx"],
      "env": {
        "CIRCULARA_BACKEND_URL": "your-value",
        "CIRCULARA_TENANT_ID": "your-value",
        "CIRCULARA_TOKEN": "your-value",
        "CIRCULARA_SEAT_ID": "your-value",
        "CIRCULARA_USER_ID": "your-value",
        "CIRCULARA_MASTER_KEY": "your-value",
        "CIRCULARA_AGENT_TOKEN_SECRET": "your-value"
      }
    }
  }
}

Add to claude_desktop_config.json, then restart Claude Desktop.

Configuration

VariableDescriptionRequired
CIRCULARA_BACKEND_URLEndpoint or connection string the server talks to.Yes
CIRCULARA_TENANT_IDConfiguration value read at startup.Optional
CIRCULARA_TOKENCredential the server authenticates with.Yes
CIRCULARA_SEAT_IDConfiguration value read at startup.Optional
CIRCULARA_USER_IDConfiguration value read at startup.Optional
CIRCULARA_MASTER_KEYCredential the server authenticates with.Yes
CIRCULARA_AGENT_TOKEN_SECRETCredential the server authenticates with.Yes

Example prompts to try

  • “Use Plugin to Humans.”
  • “Use Plugin to Gateway.”
  • “Use Plugin to OIDC.”

Frequently asked questions

It connects Plugin to MCP-compatible AI assistants such as Claude and Cursor, exposing 4 tools (Humans, Gateway, OIDC, and more) that the assistant can call on your behalf. Instead of copying data back and forth by hand, the assistant works with Plugin directly.

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