Unverified50% confidenceFactExact time
When an agent holding a read-only token attempts to perform a write operation, the MCP server returns 403 Forbidden and indicates Insufficient Scope.
1
Sources
50%
Confidence
Long-term
Relevance
10/10/2026
First Seen
Sources
Related Entities
Related Claims
UnverifiedWhen an AI agent first attempts to access a protected MCP server, the server returns a 401 Unauthorized response and indicates the location of the authorization server in the response header.74% similarUnverifiedAnnotation declarations on MCP servers have no enforcement validation mechanism at the protocol level, creating a supply-chain trust problem where an attacker can publish a malicious server claiming to be read-only while performing arbitrary write operations.73% similarUnverifiedWithout rigorous authentication, permission isolation, and input validation, a hijacked agent may cause damage to backend systems via an MCP server.69% similarVerifiedMCP tool annotations (such as read-only, destructive, idempotent, and open-world) are hints rather than guarantees, and applications should treat them as untrusted information unless the server itself is trusted.67% similarUnverifiedThe official Learn documentation notes that autonomously running or misconfigured clients may execute destructive operations, and that flags for blocking destructive operations have not yet been standardized in the MCP protocol.66% similar
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