# X_MCP_TENANT_UNRESOLVED

## Means

the tenant of an MCP call could not be resolved

## Typical cause

defineAppMcp({ tenant: { resolve } }) threw, or answered an actor that is not an agent — a failed lookup is never read as "not a member"

## Fix

`defineAppMcp({ tenant: { arg, resolve: ({ person, value }) => (member ? agentActor({ id: person.id, orgId: value }) : null), list } })` — the cause names what refused; `resolve` answers a `kind: 'agent'` actor, or `null` for a non-member, and never throws

[MCP and AI](/error-codes#mcp-and-ai)