MCP gateway doesn't enforce all of a tool's published input schema #8575

platform_export_snapshot declares components.envVars as "all" | "keys" | false, and the published JSON Schema says exactly that:

"envVars": { "anyOf": [
  { "type": "string", "enum": ["all", "keys"] },
  { "type": "boolean", "const": false }
]}

Passing components: {envVars: true} sails past the gateway anyway and reaches the route, which bounces it as a bare Bad Request with no indication of which field was wrong.

Other keywords are enforced fine, so this looks specific rather than general:

• additionalProperties: components: {nodes: false} is caught, Input validation error: ... components.nodes: unrecognized key
• minLength: platform_update_snapshot declares name as z.string().min(1), and name: "" is caught, Input validation error: ... name: shorter than minLength 1
• pattern: platform_set_instance_device_target declares hostedInstanceId as a UUID, and a non-UUID is caught, Input validation error: ... hostedInstanceId: does not match pattern ^([0-9a-fA-F]{8}-...
• const on that boolean branch: not caught

Fallout is small on its own (the route catches it), but it means a tool can't fully rely on its declared schema for validation, and the agent gets a vague error instead of one naming the field. Related to #8572, which is about how errors come back rather than which ones get caught.