Connect Codex

Preview Connecting Codex to the Atlan MCP endpoint lets Codex find registry artifacts and inspect skills while you work in a repository. Use it when you work in the Codex CLI, IDE extension, or desktop app: all three share one MCP configuration. Codex has no Open in handoff from a skill profile, so this connection is how Codex reaches skills.

Before you begin

Before you start, make sure you have:

Codex: A current version with Streamable HTTP MCP support.
Atlan account: Access to the workspaces whose artifacts and tools you expect to use. This integration is in Preview and is not enabled for every account.

Add Atlan MCP endpoint

codex mcp add atlan --url https://api.atlan.com/mcp

This writes an [mcp_servers.atlan] entry with the URL to your Codex configuration. Project-level configuration loads only for projects Codex trusts. Keep credentials out of the configuration file and repository.This connects in search mode, the default: the client sees five tools: mcp__search_tools, mcp__describe_tools, and the runners mcp__call_read_tool, mcp__call_write_tool, and mcp__call_tool. To list every tool by name, use https://api.atlan.com/mcp?tools=full as the URL. Full mode will be deprecated later.

Decide how Codex approves tool calls

In search mode, every tool call runs through one of three runners: mcp__call_read_tool for tools that only read, mcp__call_write_tool for tools that write but are declared not destructive, and mcp__call_tool for any tool. Codex sees the runner, not the tool. mcp__call_tool is marked as a tool that can change or delete data, so Codex requires approval for each call to it, and codex exec refuses the call with MCP tool call requires approval, but approval policy is never.The approval in Codex is separate from the gateway’s own checks: whatever Codex allows, MCP Gateway still refuses a call your Atlan permissions do not cover. Pick the setup that matches how much you want Codex to ask:

Setup	Reads	Writes declared not destructive	Other tools	`codex exec`
Search mode, `approval_mode = "approve"` for `mcp__call_read_tool` and `mcp__call_write_tool`	Runs	Runs	Codex asks	Refuses calls through `mcp__call_tool`
Search mode, `approval_mode = "approve"` for all three runners	Runs	Runs	Runs	Runs every call
Full mode, `default_tools_approval_mode = "writes"`	Runs	Codex asks	Codex asks	Refuses calls that need approval

To run reads and writes without a prompt and still be asked before anything else, add this to ~/.codex/config.toml, then restart Codex:

[mcp_servers.atlan.tools.mcp__call_read_tool]
approval_mode = "approve"

[mcp_servers.atlan.tools.mcp__call_write_tool]
approval_mode = "approve"

A tool’s runner comes from its own labels, so a tool labelled read-only that writes runs through mcp__call_read_tool. Approving mcp__call_tool the same way approves every tool you can reach through the gateway, including tools that delete data. Your Atlan permissions still apply to each call.

Full mode also works: Codex then sees each tool’s own marks, and with writes it asks before every tool that is not marked read-only. This needs Codex 0.144 or later, and full mode will be deprecated later.

[mcp_servers.atlan]
url = "https://api.atlan.com/mcp?tools=full"
default_tools_approval_mode = "writes"

Verify connection

Check server: Run codex mcp list and confirm that atlan is listed.
Check tools: In an interactive session, run /mcp and inspect atlan, then ask a read-only task from Example prompts.

Codex does not call a tool just because the server is connected; ask for the task. The tools available depend on your account, workspace access, and permissions, and tool names can differ from the source names in this documentation.

Example prompts

Each prompt is read-only and uses the tools your identity can reach. Replace the example names with your own. Use the agreed metric instead of new SQL

Find the released metric for average order value in Atlan and use its calculation in this query instead of writing my own.

Reuse a trusted query

Search our saved queries in Atlan for weekly active users and adapt the matching one for this report.

Match your data model to business terms

Get the Atlan ontology context for Customer and Order so this data model matches how our business defines them.

Troubleshooting

If sign-in repeats or never completes, see Atlan sign-in repeats or never completes. For a missing server, missing tools, or refused calls, see MCP Gateway errors. For transports, authentication, and configuration scope, see the Codex MCP documentation.

Next steps

Publish skills from coding agent: Inventory local skills and publish them with aireg.

Connect coding agents

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Docs for AI agents

Before you begin

Example prompts

Troubleshooting

Next steps

See also