Schema validator
Checks field shape and basic types.
Does not establish
Cross-tool meaning, declared hand-offs or review boundaries.
Guide 10 // Connection boundaries
A VALID MESSAGE IS NOT ALWAYS A COHERENT CONNECTION.
Schema validation, gateways, permissions and Agent Preflight solve different problems. A reliable agent-tool chain often needs more than one of them.
01 // the question each layer answers
CHECK THE MESSAGE. THEN CHECK THE HAND-OFF.
A schema validator asks whether a message has the expected shape. An API gateway asks whether a request may reach a route. MCP permissions ask whether a client may call a tool. Agent Preflight asks whether a declared connection can be understood, checked and taken forward for review within explicit boundaries.
API gateway
Checks transport, routing and access rules.
Does not establish
Agent-tool semantics or workflow composition.
MCP permissions
Checks whether a client may call a tool.
Does not establish
Whether the declared connection is coherent.
Ingress Shield
Checks declared connection seams, boundaries and review evidence.
Does not establish
Permission to execute, sign, activate or deploy work.
02 // what it can expose
VALID PARTS CAN STILL FAIL AT THE SEAM.
Depending on the declared contracts and workflow description available for review, Agent Preflight can identify a JSON-valid output with no declared downstream consumer; a required input with no declared producer; schemas that fit structurally but conflict in meaning, units or expectations; or an assumed adapter that is not declared.
It can also identify a technically compatible connection with no declared authority or review boundary, or a proposal that cannot be tied to declared component and contract identities plus a reviewable result.
CHECK FIRST
Connection seams
Agent Preflight examines the declared relationship between parts. It does not infer permission from technical compatibility.
03 // why the combination matters
THE USEFUL PART IS KEEPING THE CONTEXT CONNECTED.
Individual checks can be straightforward. The useful part is keeping declared identity, typed interfaces, authority boundaries and redacted evidence connected around the same proposed hand-off.
That gives a reviewer a clearer question: what fits, what does not, and what needs to change before the connection is considered further.
04 // what a passing result means
FIT FOR REVIEW. NOT PERMISSION TO RUN.
A passing preflight result means the declared connection was sufficiently coherent for review against the available bounded information. It is not permission to execute, sign, activate, deploy or change work.
Agent Preflight complements schema validation, API gateways and MCP permissions. It does not replace them.