How to meet it
OWASP AISVS v1.01
Model Context Protocol (MCP) Security · Authentication & Authorization
Authorise every MCP tool call
Verify that MCP servers enforce access control on every tool invocation, validating that the user's access token authorizes both the requested tool and the specific argument values supplied.
OWASP AISVS v1.01, requirement 10.2.5
In plain English
On every tool call, check the user's token allows both that tool and the specific argument values.
What good looks like
- Tool and argument values are checked per call.
- Disallowed values are rejected.
- Rejections are logged.
How teams usually do it
- Policy checks in the server's call handler.
Evidence an auditor would accept
- Tests with allowed tools and disallowed arguments.
Common mistakes
- Checking the tool name and accepting any arguments.
Not sure which requirements apply to your system? Take the assessment.
Requirement text from the OWASP AI Security Verification Standard, licensed under CC BY-SA 4.0. This guidance is shared under the same licence.