Filter MCP tool visibility and invocation by the requesting API token's
(group, permission) scopes. tools/list now returns only the tools the
token's APIPermissions authorise; tools/call additionally re-checks the
scope in the dispatcher as defence-in-depth, so a session created with
one token cannot be reused to invoke tools that token never had access to.
The per-session filter runs at session-init via the StreamableHTTPHandler
getServer factory (which the SDK calls once per session, before caching
the *mcp.Server). The dispatcher check runs on every tools/call and
returns ErrScopeDenied, which the AddTool wrapper renders as an IsError
tool result.
kolaente