Esa Gaia MCP server

@pipeworx/esa-gaia

ESA Gaia DR3 — positions, parallaxes (hence distances), proper motions, photometry and astrophysical parameters for 1.8 billion stars, queried over the ESA archive's TAP service.

Part of Pipeworx — an MCP gateway connecting AI agents to 1679+ live data sources.

Tools

every star inside a radius of a sky position, nearest first, with distances derived from parallax.

• gaiaconesearch(ra, dec, radiusarcmin?, maxmagnitude?, minparallaxmas?, limit?) —

archive, row-capped at 2,000.

• gaiasourcebyid(sourceid) — one star's full astrometric and photometric record.
• gaiaadqlquery(query, limit?) — an arbitrary read-only ADQL SELECT against the

Auth

Keyless — the synchronous TAP endpoint needs no account.

Data sources

Main table gaiadr3.gaia_source.

• — IVOA TAP, ADQL, FORMAT=json.

Things the next person would otherwise rediscover

carrying the error, so a naive caller books a failure as an empty result. A JSON body with no data array is therefore treated as an error and the text surfaced.

• TAP answers a REJECTED query with HTTP 200 and a VOTable element

with noise, not a distance: roughly a fifth of faint sources have a negative value. 1000/parallax is a distance in parsecs only when the parallax is positive and well determined, so distancepc is null — with a distancenote saying why — for a negative parallax or a signal-to-noise below 5. Inverting it anyway produces a confident-looking number that means nothing.

• Parallax is in milliarcseconds and can be NEGATIVE. It is a measurement

above 2^53 by the time the body is parsed, so ids are re-rendered as strings on the way out and accepted as strings on the way in.

• sourceid is a 64-bit integer.** JSON.parse has already lost precision

larger TOP silently**, so the cap is applied here explicitly rather than trusted to the server.

• sourceid values are release-specific** — a DR2 id does not resolve in DR3.
• **The anonymous sync endpoint caps results at 2,000 rows and truncates a

radius_arcmin defaults to 3 and is capped at 60 for that reason.

• Gaia is dense. A 1-degree cone in the galactic plane is millions of stars;

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "esa-gaia": {
      "url": "https://gateway.pipeworx.io/esa-gaia/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/esa-gaia/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — askpipeworx, discovertools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Both URLs reach the same gateway and the same 1679+ data sources. The only difference is which pack's tools are listed directly; ask_pipeworx reaches all of them from either one.

No MCP client? Call it over HTTP

Shortened. The full README is on GitHub.