Check catalogue¶

68 rules. IDs are stable and never reused. Severities are defaults; some checks adjust them per spec revision or evidence.

Transport¶

ID	Title	Severity	Mode	Revisions
MCPP-TRN01	MCP endpoint not served over HTTPS	`critical`	passive	all
MCPP-TRN02	Legacy TLS (1.0/1.1) accepted	`high`	passive	all
MCPP-TRN03	TLS certificate invalid or expiring	`high`	passive	all
MCPP-TRN04	Plain HTTP not redirected to HTTPS	`medium`	passive	all
MCPP-TRN05	HSTS header missing	`low`	passive	all
MCPP-TRN06	Legacy HTTP+SSE transport only	`medium`	passive	all
MCPP-TRN07	Session identifier carried in a URL	`high`	passive	all
MCPP-TRN08	Weak Mcp-Session-Id	`high`	passive	2025-03-26 to 2025-11-25
MCPP-TRN09	Session ID minted on a stateless revision	`info`	passive	2026-07-28
MCPP-TRN10	Weak security headers on discovery endpoints	`low`	passive	all
MCPP-TRN11	MCP endpoint redirects	`info`	passive	all

ID	Title	Severity	Mode	Revisions
MCPP-AUTHN01	MCP tools listed without authentication	`high`	passive	all
MCPP-AUTHN02	401 without a Bearer challenge	`medium`	passive	all
MCPP-AUTHN03	No way to discover Protected Resource Metadata	`high`	passive	2025-06-18 and later
MCPP-AUTHN04	resource_metadata URL not HTTPS or on another origin	`medium`	passive	2025-06-18 and later
MCPP-AUTHN05	Error code in an unauthenticated challenge	`low`	passive	all
MCPP-AUTHN06	Error responses leak internals	`medium`	passive	all

ID	Title	Severity	Mode	Revisions
MCPP-PRM01	Protected Resource Metadata not found	`high`	passive	2025-06-18 and later
MCPP-PRM02	Protected Resource Metadata malformed	`medium`	passive	2025-06-18 and later
MCPP-PRM03	PRM resource does not match the server URL	`high`	passive	2025-06-18 and later
MCPP-PRM04	PRM lists no authorization server	`high`	passive	2025-06-18 and later
MCPP-PRM05	Authorization server issuer not HTTPS	`high`	passive	2025-06-18 and later
MCPP-PRM06	Bearer tokens accepted in the query string	`high`	passive	2025-06-18 and later
MCPP-PRM07	PRM does not list scopes	`low`	passive	2025-06-18 and later
MCPP-PRM08	PRM resource has a fragment or query	`high`	passive	2025-06-18 and later
MCPP-PRM09	Unsafe signed_metadata	`medium`	passive	2025-06-18 and later
MCPP-PRM10	offline_access advertised by the resource	`low`	passive	2026-07-28
MCPP-PRM11	PRM variants disagree	`medium`	passive	2025-06-18 and later

ID	Title	Severity	Mode	Revisions
MCPP-ASM01	Authorization server metadata not found	`high`	passive	2025-06-18 and later
MCPP-ASM02	Issuer mismatch	`high`	passive	all
MCPP-ASM03	Authorization server endpoint not HTTPS	`high`	passive	all
MCPP-ASM04	PKCE S256 not advertised	`critical`	passive	all
MCPP-ASM05	PKCE plain method allowed	`high`	passive	all
MCPP-ASM06	Deprecated grant types enabled	`high`	passive	all
MCPP-ASM07	Response types incompatible with OAuth 2.1	`medium`	passive	all
MCPP-ASM08	Resource indicator (RFC 8707) enforcement not verified	`info`	passive	2025-06-18 and later
MCPP-ASM09	Dynamic Client Registration endpoint exposed	`info`	passive	all
MCPP-ASM10	Dynamic Client Registration without Client ID Metadata Documents	`low`	passive	2025-11-25 and later
MCPP-ASM11	Authorization response iss parameter not supported	`low`	passive	2025-06-18 and later
MCPP-ASM12	Unsigned (alg=none) client authentication allowed	`medium`	passive	all
MCPP-ASM13	Default authorization endpoints without metadata (2025-03-26)	`medium`	passive	2025-03-26

ID	Title	Severity	Mode	Revisions
MCPP-CIMD01	Client ID Metadata Documents not advertised	`low`	passive	2025-11-25 and later
MCPP-CIMD02	Client registration strategies	`info`	passive	all
MCPP-CIMD50	Invalid client identifier URL	`high`	lint	2025-11-25 and later
MCPP-CIMD51	Document client_id does not match its URL	`high`	lint	2025-11-25 and later
MCPP-CIMD52	Required client metadata missing	`medium`	lint	2025-11-25 and later
MCPP-CIMD53	Unsafe redirect URI	`medium`	lint	2025-11-25 and later
MCPP-CIMD54	Shared secret in a public metadata document	`critical`	lint	2025-11-25 and later
MCPP-CIMD55	Private key material in the document	`critical`	lint	2025-11-25 and later
MCPP-CIMD56	Authentication method inconsistent with key material	`medium`	lint	2025-11-25 and later
MCPP-CIMD57	Document not served the way authorization servers fetch it	`medium`	lint	2025-11-25 and later

ID	Title	Severity	Mode	Revisions
MCPP-SCP01	Over-broad scopes advertised	`medium`	passive	2025-06-18 and later
MCPP-SCP02	Challenge does not name the required scope	`low`	passive	2025-11-25 and later
MCPP-SCP04	Resource scopes unknown to the authorization server	`info`	passive	2025-06-18 and later

ID	Title	Severity	Mode	Revisions
MCPP-TOOL01	Instruction-like text in a tool description	`high`	passive	all
MCPP-TOOL02	Invisible or bidirectional Unicode in tool metadata	`high`	passive	all
MCPP-TOOL03	Encoded blob in tool metadata	`medium`	passive	all
MCPP-TOOL04	Tool description references other tools (shadowing)	`medium`	passive	all
MCPP-TOOL05	Sensitive paths or suspicious URLs in tool metadata	`medium`	passive	all
MCPP-TOOL06	Abnormally long tool metadata	`low`	passive	all
MCPP-TOOL07	Tool annotations contradict the tool's name	`low`	passive	all
MCPP-TOOL08	Tool accepts arbitrary URLs, paths or code	`low`	passive	all
MCPP-TOOL09	Confusable or colliding tool names	`medium`	passive	all
MCPP-TOOL10	Tool metadata nested too deeply to inspect	`medium`	passive	all

ID	Title	Severity	Mode	Revisions
MCPP-PIN01	Tool surface item added since the baseline	`medium`	passive	all
MCPP-PIN02	Tool surface item removed since the baseline	`low`	passive	all
MCPP-PIN03	Tool definition changed since the baseline (rug pull)	`high`	passive	all
MCPP-PIN04	Target not covered by the baseline	`info`	passive	all