> ## Documentation Index
> Fetch the complete documentation index at: https://docs.oriant.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Argument rules

> Limit the values an MCP tool may be called with on one connection, such as one Linear team or one Slack channel.

An **argument rule** limits the values one tool on one MCP Connection may be called with. Use it to keep a tool inside one team, project or channel.

A rule has four parts:

* **The argument**: one top-level argument of the tool.
* **only** or **never**: the value must, or must not, match.
* **is** or **contains**: match the whole value or part of the text.
* Matching ignores case.

Oriant adds each rule to the tool's description, so the AI client knows the limit before it calls. Before forwarding, Oriant checks the call. A call that breaks a rule is recorded as refused with reason `argument_not_allowed` and never sent.

> [!NOTE]
>
> Rules check what a call asks for, not what the server returns.


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