Do not open a public issue for a suspected vulnerability. Send a private security report through the repository's GitHub Security Advisory page.

Include the affected package version, browser version, a minimal reproduction, and the expected security impact. Please avoid including real credentials or personal data.

WebMCP tools execute inside the application page and have the same authority as that page's Dart code. Applications are responsible for authentication, authorization, confirmation of destructive actions, input validation, and protecting sensitive results.

Tool annotations are hints to agents, not access controls. Restrict cross-origin discovery with exposedTo, use HTTPS, and apply an appropriate Permissions-Policy header where WebMCP must be disabled.

WebMcp.logger can receive tool inputs, outputs, errors, and stack traces. Do not send these diagnostics to telemetry without redacting secrets and personal data.