---
schema_version: "1"
id: 4496ddaa0219348867b557e2325485008011a46a77d8cbe45b54eabbdcc256dd
title: MCP Schema Validation Policy
collection: mulesoft
version: current
locale: en-us
portal_url: https://docs.salesforce.com/mulesoft/current/en-us/gateway/1.12/policies-included-mcp-schema-validation.md
canonical_url: https://docs.mulesoft.com/gateway/1.12/policies-included-mcp-schema-validation
source_site: docs.mulesoft.com
content_type: documentation
content_hash: 9ab801fc16681e3e239eef2686d605bfff16af6b955dbdad3cc3b1cf266f29ff
description: MuleSoft Documentation Site
release: "1.12"
latest: false
---
---
product: Omni Gateway
version: 1.12
keywords: api gateway, flex gateway, gateway, policy
---

# MCP Schema Validation Policy

> For the full documentation index, see: https://docs.mulesoft.com/llms.txt

<table><colgroup><col> <col></colgroup><tbody><tr><td><p><strong>Policy Name</strong></p></td><td><p>MCP Schema Validation</p></td></tr><tr><td><p><strong>Summary</strong></p></td><td><p>Validates MCP requests to ensure they conform to the MCP specification</p></td></tr><tr><td><p><strong>Category</strong></p></td><td><p>MCP</p></td></tr><tr><td><p><strong>First Flex Gateway version available</strong></p></td><td><p>v1.9.3</p></td></tr><tr><td><p><strong>Returned Status Codes</strong></p></td><td></td></tr></tbody></table>

> [!NOTE] This policy supports Model Context Protocol (MCP) version 2025-06-18 and earlier. To learn
> more about MCP, see [MCP Specification](https://modelcontextprotocol.io/specification/2025-06-18).

## Summary

The MCP Schema Validation policy validates that every incoming request complies with JsonRPC MCP
protocol.

When **Validate Tool Schema** is enabled, the policy also:

- Validates tool invocation request parameters against the JSON schema of the tool.

- Returns the tools/list MCP request without having to send the request to the upstream MCP Server.

When the policy can’t validate the request, it returns an
[MCP Error Response](https://modelcontextprotocol.io/specification/2025-11-25/basic#error-responses).

### Flex Gateway Local Mode

The MCP Schema Validation policy isn’t supported in Local Mode.

### Managed Flex Gateway and Flex Gateway Connected Mode

When you apply the policy from the UI, the following parameters are displayed:

<table><colgroup><col> <col></colgroup><thead><tr><th>Parameter</th><th>Description</th></tr></thead><tbody><tr><td><div><div><p>Validate Tool Schema</p></div></div></td><td><div><div><p>When enabled, the policy:</p></div><div><ul><li><p>Validates tool invocation request parameters against the JSON schema of the tool.</p></li><li><p>Returns the tools/list MCP request without having to send the request to the upstream MCP Server.</p></li></ul></div></div></td></tr></tbody></table>