Athanor by arbastro
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For developers

Athanor MCP server

A remote Model Context Protocol server that gives AI assistants Athanor’s chemistry engine: convert, name, describe, draw, check, screen and look up structures. It is free, needs no account, and keeps nothing.

Endpoint
https://mcp-athanor.arbastro.com/mcp
Transport
Streamable HTTP; protocol versions 2025-03-26 and 2025-06-18
Authentication
None for the tools below
Limits
60 calls a minute from one address; structures up to 20,000 characters
Input
SMILES, a molfile, an InChI or a common name

Set it up

Pick your client. Any other client that supports remote MCP servers over Streamable HTTP works with the endpoint above.

Client
  1. Open Settings > Apps & Connectors > Advanced settings and turn on Developer mode.
  2. Back in Apps & Connectors, choose Create.
  3. Name it Athanor, set MCP server URL to https://mcp-athanor.arbastro.com/mcp, and set Authentication to No authentication.
  4. Tick that you trust the connector, then choose Create.

Tools

convertConverts a structure to canonical SMILES, a MOL V3000 or V2000 block, or XYZ with 3D coordinates.
nameThe systematic IUPAC name worked out from the structure, and the common name when the library knows it.
propertiesFormula, charge, exact and average mass, and descriptors such as H-bond donors and acceptors, TPSA and a logP estimate.
depictA 2D drawing of the structure as SVG, in the ACS Document 1996 journal style or another preset.
checkEvery problem the editor would flag: valence, charges, stereo and drawing issues, each with its fix.
screenSafety screening as a synthesis target against controlled-substance schedules, the CWC and the Australia Group list.
library_searchLooks a compound up in Athanor’s library by name, synonym or CAS number.

Each tool reads only the arguments of its own call. Try name and depict on the chemistry MCP server page.

Your data

The server receives the arguments of each tool call, which are structures and options, never your conversation with the assistant. It returns a result and keeps nothing. See Privacy and Trust.

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