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

# Skip Tool Input Validation

> Bypass strict MCP input schema validation for malformed upstream servers

## What is Skip Tool Input Validation?

Runlayer normally validates tool call arguments against each tool's MCP input schema before forwarding the call upstream. This catches malformed requests early and keeps payload-based policies predictable.

Some upstream MCP servers publish invalid JSON schemas that otherwise work in clients with looser validation. Enable **Skip Tool Input Validation** only for those servers.

## When to Enable This

Enable this when a connector fails before the tool reaches the upstream server because its published input schema is malformed, but the same tool works in a client that does not strictly validate schemas.

<Warning>
  This setting reduces Runlayer's ability to reason about tool arguments before execution. Prefer fixing or wrapping the upstream server when practical.
</Warning>

## PBAC Limitation

Server-scoped payload-based PBAC conditions cannot be configured for servers with this setting enabled.

This includes policy fields like `payload.department_id` and value references like `$payload.repo`. Without schema validation, missing or malformed tool arguments can make negative conditions such as `not_equals` behave unexpectedly.

Global wildcard policies can still use payload-based conditions and may still evaluate for these servers.

Policies that use `meta.*` fields, server scope, tool scope, resource scope, principals, groups, roles, and attributes still work normally.

## How to Enable

1. Go to **MCPs** and select your server
2. Open server settings
3. Enable **Skip Tool Input Validation**
4. Save changes

If matching server-scoped policies already use payload-based conditions, remove those conditions before enabling this setting.