fix(core): allow extra JSON Schema keys in elicit primitive schemas

Add .passthrough() to all primitive schema definitions used in
ElicitRequestFormParamsSchema. Schemas generated by z.toJSONSchema()
with constraints like .regex(), .min(), .max() produce extra keys
(pattern, exclusiveMinimum, format, const, etc.) that were rejected
by the strict z.object() definitions.

.passthrough() preserves type safety for known fields while allowing
unknown JSON Schema keywords to flow through, matching how
inputSchema/outputSchema already handle this.

Closes #1844

Author: claygeo

.changeset/elicit-schema-passthrough.md

@@ -0,0 +1,5 @@
+---
+'@modelcontextprotocol/core': patch
+---
+
+Allow extra JSON Schema keys (pattern, exclusiveMinimum, format, const, etc.) in elicit primitive schemas. Schemas generated by z.toJSONSchema() with constraints like .regex() or .min() are now accepted instead of rejected.

packages/core/src/types/schemas.ts

@@ -1722,7 +1722,7 @@ export const BooleanSchemaSchema = z.object({
     title: z.string().optional(),
     description: z.string().optional(),
     default: z.boolean().optional()
-});
+}).passthrough();
 
 /**
  * Primitive schema definition for string fields.
@@ -1735,7 +1735,7 @@ export const StringSchemaSchema = z.object({
     maxLength: z.number().optional(),
     format: z.enum(['email', 'uri', 'date', 'date-time']).optional(),
     default: z.string().optional()
-});
+}).passthrough();
 
 /**
  * Primitive schema definition for number fields.
@@ -1747,7 +1747,7 @@ export const NumberSchemaSchema = z.object({
     minimum: z.number().optional(),
     maximum: z.number().optional(),
     default: z.number().optional()
-});
+}).passthrough();
 
 /**
  * Schema for single-selection enumeration without display titles for options.
@@ -1758,7 +1758,7 @@ export const UntitledSingleSelectEnumSchemaSchema = z.object({
     description: z.string().optional(),
     enum: z.array(z.string()),
     default: z.string().optional()
-});
+}).passthrough();
 
 /**
  * Schema for single-selection enumeration with display titles for each option.
@@ -1774,7 +1774,7 @@ export const TitledSingleSelectEnumSchemaSchema = z.object({
         })
     ),
     default: z.string().optional()
-});
+}).passthrough();
 
 /**
  * Use {@linkcode TitledSingleSelectEnumSchema} instead.
@@ -1787,7 +1787,7 @@ export const LegacyTitledEnumSchemaSchema = z.object({
     enum: z.array(z.string()),
     enumNames: z.array(z.string()).optional(),
     default: z.string().optional()
-});
+}).passthrough();
 
 // Combined single selection enumeration
 export const SingleSelectEnumSchemaSchema = z.union([UntitledSingleSelectEnumSchemaSchema, TitledSingleSelectEnumSchemaSchema]);
@@ -1806,7 +1806,7 @@ export const UntitledMultiSelectEnumSchemaSchema = z.object({
         enum: z.array(z.string())
     }),
     default: z.array(z.string()).optional()
-});
+}).passthrough();
 
 /**
  * Schema for multiple-selection enumeration with display titles for each option.
@@ -1826,7 +1826,7 @@ export const TitledMultiSelectEnumSchemaSchema = z.object({
         )
     }),
     default: z.array(z.string()).optional()
-});
+}).passthrough();
 
 /**
  * Combined schema for multiple-selection enumeration