diff --git a/packages/mxfx/src/api/endpoints/auth/post-login-v3.ts b/packages/mxfx/src/api/endpoints/auth/post-login-v3.ts
index f6fae69..06b66a7 100644
--- a/packages/mxfx/src/api/endpoints/auth/post-login-v3.ts
+++ b/packages/mxfx/src/api/endpoints/auth/post-login-v3.ts
@@ -1,8 +1,7 @@
-import { Effect, Schema } from 'effect'
-import { HttpBody } from 'effect/unstable/http'
+import { Schema } from 'effect'
 
-import { encodeSnakeCaseSchema } from '../../schema/encode-case.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const commonOptionsSchema = Schema.Struct({
   initialDeviceDisplayName: Schema.optional(Schema.String),
@@ -47,9 +46,4 @@ const schema = Schema.Struct({
  * @see https://spec.matrix.org/v1.17/client-server-api/#post_matrixclientv3login
  */
 export const postLoginV3 = (options: Schema.Schema.Type<typeof optionsSchema>) =>
-  Effect.gen(function* () {
-    //TODO: this is weird encodeSnakeCaseSchema should not be exposed like this
-    const body = yield* Schema.encodeEffect(optionsSchema.pipe(encodeSnakeCaseSchema))(options).pipe(Effect.andThen(HttpBody.json))
-
-    return yield* makeEndpoint('POST', { auth: false, body, schema })`/v3/login`
-  })
+  makeEndpoint('POST', { auth: false, body: RequestOptions.body(optionsSchema, options), schema })`/v3/login`
diff --git a/packages/mxfx/src/api/endpoints/discovery/get-well-known.ts b/packages/mxfx/src/api/endpoints/discovery/get-well-known.ts
index 53de4fa..a346dae 100644
--- a/packages/mxfx/src/api/endpoints/discovery/get-well-known.ts
+++ b/packages/mxfx/src/api/endpoints/discovery/get-well-known.ts
@@ -1,7 +1,8 @@
 import { Schema } from 'effect'
 
-import type { ServerName } from '../../../branded/server-name.ts'
+import { ServerName } from '../../../branded/server-name.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const schema = Schema.Struct({
   'm.homeserver': Schema.Struct({
@@ -18,4 +19,8 @@ const schema = Schema.Struct({
  * @see https://spec.matrix.org/v1.17/client-server-api/#getwell-knownmatrixclient
  */
 export const getWellKnown = ({ serverName }: { serverName: ServerName }) =>
-  makeEndpoint('GET', { auth: false, schema, encode: false })`https://${serverName}/.well-known/matrix/client`
+  makeEndpoint('GET', {
+    auth: false,
+    schema,
+    encode: false,
+  })`https://${RequestOptions.path(ServerName.schema, serverName)}/.well-known/matrix/client`
diff --git a/packages/mxfx/src/api/endpoints/endpoint.ts b/packages/mxfx/src/api/endpoints/endpoint.ts
index 5e92320..919f707 100644
--- a/packages/mxfx/src/api/endpoints/endpoint.ts
+++ b/packages/mxfx/src/api/endpoints/endpoint.ts
@@ -2,6 +2,7 @@ import { Effect, Schema } from 'effect'
 import { HttpBody, HttpClientRequest, HttpClientResponse, UrlParams } from 'effect/unstable/http'
 
 import { encodeSnakeCaseSchema } from '../schema/encode-case.ts'
+import * as RequestOptions from './request-options.ts'
 
 export type MatrixEndpoint<S extends Schema.Top> = {
   path: typeof pathBrandSchema.Type
@@ -20,40 +21,58 @@ const makeEndpointFromConfig = <S extends Schema.Top>(endpoint: MatrixEndpoint<S
 
 type PathValue = string | number
 
+type EndpointBuilder<S extends Schema.Top> = (
+  strings: TemplateStringsArray,
+  ...values: readonly (PathValue | RequestOptions.Path)[]
+) => Effect.Effect<MatrixEndpoint<S>, HttpBody.HttpBodyError | Schema.SchemaError>
+
 type EndpointBaseOptions<S extends Schema.Top> = {
   schema: S
-  params?: UrlParams.Input
+  query?: RequestOptions.Query
   encode?: boolean
 }
 
 type EndpointWithBodyOptions<S extends Schema.Top> = EndpointBaseOptions<S> & {
   auth: boolean
-  body?: HttpBody.HttpBody
+  body?: RequestOptions.Body
 }
 
 type GetOptions<S extends Schema.Top> = EndpointBaseOptions<S> & { auth: boolean }
 type WriteOptions<S extends Schema.Top> = EndpointWithBodyOptions<S>
 
-export function makeEndpoint<S extends Schema.Top>(
-  method: 'GET',
-  options: GetOptions<S>,
-): (strings: TemplateStringsArray, ...values: readonly PathValue[]) => Effect.Effect<MatrixEndpoint<S>>
+export function makeEndpoint<S extends Schema.Top>(method: 'GET', options: GetOptions<S>): EndpointBuilder<S>
 export function makeEndpoint<S extends Schema.Top>(
   method: 'POST' | 'PUT' | 'DELETE' | 'PATCH',
   options: WriteOptions<S>,
-): (strings: TemplateStringsArray, ...values: readonly PathValue[]) => Effect.Effect<MatrixEndpoint<S>>
+): EndpointBuilder<S>
 export function makeEndpoint<S extends Schema.Top>(method: MatrixEndpoint<S>['method'], options: GetOptions<S> | WriteOptions<S>) {
+  return make(method, options)
+}
+
+const make = <S extends Schema.Top>(method: MatrixEndpoint<S>['method'], options: GetOptions<S> | WriteOptions<S>) => {
   const encode = options.encode ?? true
 
-  return (strings: TemplateStringsArray, ...values: readonly PathValue[]) =>
-    makeEndpointFromConfig({
-      auth: options.auth,
-      method,
-      path: apiPath({ encode })(strings, ...values),
-      params: options.params,
-      schema: options.schema,
-      body: method === 'GET' ? undefined : 'body' in options ? options.body : undefined,
-    } as MatrixEndpoint<S>)
+  return (strings: TemplateStringsArray, ...values: readonly (PathValue | RequestOptions.Path)[]) => {
+    const path = Effect.all(
+      values.map(value => (RequestOptions.isPath(value) ? RequestOptions.encodePath(value) : Effect.succeed(String(value)))),
+    ).pipe(Effect.map(values => apiPath({ encode })(strings, ...values)))
+    const params = options.query ? RequestOptions.encodeQuery(options.query) : Effect.succeed(UrlParams.empty)
+    const body =
+      method !== 'GET' && 'body' in options && options.body ? RequestOptions.encodeBody(options.body) : Effect.succeed(HttpBody.empty)
+
+    return Effect.all({ body, params, path }).pipe(
+      Effect.flatMap(({ body, params, path }) =>
+        makeEndpointFromConfig({
+          auth: options.auth,
+          method,
+          path,
+          params,
+          schema: options.schema,
+          body: method === 'GET' ? undefined : body,
+        } as MatrixEndpoint<S>),
+      ),
+    )
+  }
 }
 
 export const makeHttpRequest = <S extends Schema.Top>(endpoint: MatrixEndpoint<S>) =>
diff --git a/packages/mxfx/src/api/endpoints/index.ts b/packages/mxfx/src/api/endpoints/index.ts
index ac82c3f..36867be 100644
--- a/packages/mxfx/src/api/endpoints/index.ts
+++ b/packages/mxfx/src/api/endpoints/index.ts
@@ -6,3 +6,4 @@ export * from './sync/index.ts'
 export * from './profile/index.ts'
 export * from './rooms/index.ts'
 export * from './account/index.ts'
+export * as RequestOptions from './request-options.ts'
diff --git a/packages/mxfx/src/api/endpoints/profile/get-profile-v3.ts b/packages/mxfx/src/api/endpoints/profile/get-profile-v3.ts
index 4c131a8..4e04794 100644
--- a/packages/mxfx/src/api/endpoints/profile/get-profile-v3.ts
+++ b/packages/mxfx/src/api/endpoints/profile/get-profile-v3.ts
@@ -3,6 +3,7 @@ import { Schema } from 'effect'
 import { MxcUri } from '../../../branded/mxc-uri.ts'
 import { UserId } from '../../../branded/user-id.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const schema = Schema.Struct({
   avatarUrl: Schema.optional(Schema.NullOr(MxcUri.schema)),
@@ -21,7 +22,8 @@ const schema = Schema.Struct({
  *
  * @see https://spec.matrix.org/v1.17/client-server-api/#get_matrixclientv3profileuserid
  */
-export const getProfileV3 = ({ userId }: { userId: UserId }) => makeEndpoint('GET', { auth: true, schema })`/v3/profile/${userId}`
+export const getProfileV3 = ({ userId }: { userId: UserId }) =>
+  makeEndpoint('GET', { auth: true, schema })`/v3/profile/${RequestOptions.path(UserId.schema, userId)}`
 
 /*
  * TODO: explore this pattern:
diff --git a/packages/mxfx/src/api/endpoints/request-options.test.ts b/packages/mxfx/src/api/endpoints/request-options.test.ts
new file mode 100644
index 0000000..3b34de1
--- /dev/null
+++ b/packages/mxfx/src/api/endpoints/request-options.test.ts
@@ -0,0 +1,59 @@
+import { describe, expect, it } from '@effect/vitest'
+import { Effect, Schema } from 'effect'
+
+import { makeEndpoint } from './endpoint.ts'
+import * as RequestOptions from './request-options.ts'
+
+const filterSchema = Schema.Struct({
+  eventFields: Schema.Array(Schema.String),
+})
+
+describe('RequestOptions', () => {
+  it.effect('encodes body keys as snake_case', () =>
+    Effect.gen(function* () {
+      const schema = Schema.Struct({
+        userName: Schema.String,
+        profile: Schema.Struct({ displayName: Schema.String }),
+      })
+
+      const body = yield* RequestOptions.encodeBody(RequestOptions.body(schema, { userName: 'alice', profile: { displayName: 'Alice' } }))
+
+      expect(body._tag).toBe('Uint8Array')
+      if (body._tag === 'Uint8Array') {
+        expect(JSON.parse(new TextDecoder().decode(body.body))).toStrictEqual({
+          user_name: 'alice',
+          profile: { display_name: 'Alice' },
+        })
+      }
+    }),
+  )
+
+  it.effect('encodes query keys and JSON-string values as snake_case', () =>
+    Effect.gen(function* () {
+      const schema = Schema.Struct({
+        filter: Schema.optional(Schema.fromJsonString(filterSchema)),
+        fullState: Schema.Boolean,
+      })
+
+      const query = yield* RequestOptions.encodeQuery(
+        RequestOptions.query(schema, { filter: { eventFields: ['content.body'] }, fullState: true }),
+      )
+
+      expect(query).toStrictEqual({
+        filter: '{"event_fields":["content.body"]}',
+        full_state: true,
+      })
+    }),
+  )
+
+  it.effect('encodes Schema.fromJsonString path parameters before URI encoding', () =>
+    Effect.gen(function* () {
+      const endpoint = yield* makeEndpoint('GET', { auth: true, schema: Schema.Unknown })`/filters/${RequestOptions.path(
+        Schema.fromJsonString(filterSchema),
+        { eventFields: ['content.body'] },
+      )}`
+
+      expect(endpoint.path).toBe('/filters/%7B%22event_fields%22%3A%5B%22content.body%22%5D%7D')
+    }),
+  )
+})
diff --git a/packages/mxfx/src/api/endpoints/request-options.ts b/packages/mxfx/src/api/endpoints/request-options.ts
new file mode 100644
index 0000000..c30c46f
--- /dev/null
+++ b/packages/mxfx/src/api/endpoints/request-options.ts
@@ -0,0 +1,47 @@
+import { Effect, Schema } from 'effect'
+import { HttpBody, type UrlParams } from 'effect/unstable/http'
+
+import { encodeSnakeCaseSchema } from '../schema/encode-case.ts'
+
+type RequestSchema = Schema.Top & Schema.Encoder<unknown, never>
+type PathSchema = Schema.Top & Schema.Encoder<string | number, never>
+type QuerySchema = Schema.Top & Schema.Encoder<UrlParams.Input, never>
+
+export interface Body {
+  readonly _tag: 'Body'
+  readonly effect: Effect.Effect<HttpBody.HttpBody, HttpBody.HttpBodyError>
+}
+
+export interface Path {
+  readonly _tag: 'Path'
+  readonly effect: Effect.Effect<string, Schema.SchemaError>
+}
+
+export interface Query {
+  readonly _tag: 'Query'
+  readonly effect: Effect.Effect<UrlParams.Input, Schema.SchemaError>
+}
+
+export const body = <S extends RequestSchema>(schema: S, value: S['Type']): Body => ({
+  _tag: 'Body',
+  effect: HttpBody.jsonSchema(encodeSnakeCaseSchema(schema))(value),
+})
+
+export const path = <S extends PathSchema>(schema: S, value: S['Type']): Path => ({
+  _tag: 'Path',
+  effect: Schema.encodeEffect(encodeSnakeCaseSchema(schema))(value).pipe(Effect.map(String)),
+})
+
+export const query = <S extends QuerySchema>(schema: S, value: S['Type']): Query => ({
+  _tag: 'Query',
+  effect: Schema.encodeEffect(encodeSnakeCaseSchema(schema))(value).pipe(Effect.map(encoded => encoded as UrlParams.Input)),
+})
+
+export const isPath = (value: unknown): value is Path =>
+  typeof value === 'object' && value !== null && '_tag' in value && value._tag === 'Path'
+
+export const encodeBody = ({ effect }: Body) => effect
+
+export const encodePath = ({ effect }: Path) => effect
+
+export const encodeQuery = ({ effect }: Query) => effect
diff --git a/packages/mxfx/src/api/endpoints/rooms/get-rooms-event-v3.ts b/packages/mxfx/src/api/endpoints/rooms/get-rooms-event-v3.ts
index b2954a0..ebfea0a 100644
--- a/packages/mxfx/src/api/endpoints/rooms/get-rooms-event-v3.ts
+++ b/packages/mxfx/src/api/endpoints/rooms/get-rooms-event-v3.ts
@@ -1,6 +1,7 @@
-import type { EventId, RoomId } from '../../../branded/index.ts'
+import { EventId, RoomId } from '../../../branded/index.ts'
 import { roomEvent } from '../../../schema/event.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const schema = roomEvent
 
@@ -14,5 +15,8 @@ const schema = roomEvent
  * @see https://spec.matrix.org/v1.17/client-server-api/#get_matrixclientv3roomsroomideventeventid
  */
 export const getRoomsEventV3 = ({ roomId, eventId }: { roomId: RoomId; eventId: EventId }) => {
-  return makeEndpoint('GET', { auth: true, schema })`/v3/rooms/${roomId}/event/${eventId}`
+  return makeEndpoint('GET', { auth: true, schema })`/v3/rooms/${RequestOptions.path(RoomId.schema, roomId)}/event/${RequestOptions.path(
+    EventId.schema,
+    eventId,
+  )}`
 }
diff --git a/packages/mxfx/src/api/endpoints/rooms/post-rooms-join-v3.ts b/packages/mxfx/src/api/endpoints/rooms/post-rooms-join-v3.ts
index c13cc97..2d9ae37 100644
--- a/packages/mxfx/src/api/endpoints/rooms/post-rooms-join-v3.ts
+++ b/packages/mxfx/src/api/endpoints/rooms/post-rooms-join-v3.ts
@@ -2,6 +2,7 @@ import { Schema } from 'effect'
 
 import { RoomId } from '../../../branded/room-id.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const schema = Schema.Struct({
   roomId: RoomId.schema,
@@ -19,4 +20,5 @@ const schema = Schema.Struct({
  *
  * @see https://spec.matrix.org/v1.17/client-server-api/#post_matrixclientv3roomsroomidjoin
  */
-export const postRoomsJoinV3 = ({ roomId }: { roomId: RoomId }) => makeEndpoint('POST', { auth: true, schema })`/v3/rooms/${roomId}/join`
+export const postRoomsJoinV3 = ({ roomId }: { roomId: RoomId }) =>
+  makeEndpoint('POST', { auth: true, schema })`/v3/rooms/${RequestOptions.path(RoomId.schema, roomId)}/join`
diff --git a/packages/mxfx/src/api/endpoints/rooms/put-rooms-send-v3.ts b/packages/mxfx/src/api/endpoints/rooms/put-rooms-send-v3.ts
index 99bff47..73e8edc 100644
--- a/packages/mxfx/src/api/endpoints/rooms/put-rooms-send-v3.ts
+++ b/packages/mxfx/src/api/endpoints/rooms/put-rooms-send-v3.ts
@@ -1,9 +1,8 @@
 import { Effect, Schema, Random } from 'effect'
-import { HttpBody } from 'effect/unstable/http'
 
 import { EventId, RoomId } from '../../../branded/index.ts'
-import { encodeSnakeCaseSchema } from '../../schema/encode-case.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const schema = Schema.Struct({
   eventId: EventId.schema,
@@ -19,24 +18,26 @@ const commonMessageContentSchema = Schema.Struct({
   msgtype: Schema.String,
 })
 
+const messageContentSchema = Schema.Union([
+  Schema.Struct({
+    ...commonMessageContentSchema.fields,
+    'm.newContent': Schema.Struct({ body: Schema.String, msgtype: Schema.String }),
+    'm.relatesTo': Schema.Struct({
+      relType: Schema.Literal('m.replace'),
+      eventId: EventId.schema,
+    }),
+  }),
+  commonMessageContentSchema,
+])
+
+const eventTypeSchema = Schema.Literal('m.room.message')
+
 const optionsSchema = Schema.Union([
   //TODO: support more event types
   Schema.Struct({
     ...commonOptionsSchema.fields,
-    eventType: Schema.Literal('m.room.message'),
-    content: Schema.Union([
-      Schema.Struct({
-        ...commonMessageContentSchema.fields,
-        'm.newContent': Schema.Struct({ body: Schema.String, msgtype: Schema.String }),
-        'm.relatesTo': Schema.Struct({
-          relType: Schema.Literal('m.replace'),
-          eventId: EventId.schema,
-        }),
-      }),
-      Schema.Struct({
-        ...commonMessageContentSchema.fields,
-      }),
-    ]),
+    eventType: eventTypeSchema,
+    content: messageContentSchema,
   }),
 ])
 
@@ -53,12 +54,16 @@ const optionsSchema = Schema.Union([
  * @see https://spec.matrix.org/v1.17/client-server-api/#put_matrixclientv3roomsroomidsendeventtypetxnid
  */
 export const putRoomsSendV3 = (options: typeof optionsSchema.Type) =>
-  Effect.gen(function* () {
-    const body = yield* Schema.encodeEffect(optionsSchema.pipe(encodeSnakeCaseSchema))(options).pipe(
-      Effect.andThen(({ content }) => HttpBody.json(content)),
-    )
-
-    const transactionId = options.transactionId ? options.transactionId : yield* Random.nextIntBetween(1, 10000000) // TODO: used be uuidv4 but was removed from random module into crypto, but haven't bothered to check how possible it is to DI anything here bc crypto gotta be injected
-
-    return yield* makeEndpoint('PUT', { auth: true, schema, body })`/v3/rooms/${options.roomId}/send/${options.eventType}/${transactionId}`
-  })
+  (options.transactionId ? Effect.succeed(options.transactionId) : Random.nextIntBetween(1, 10000000).pipe(Effect.map(String))).pipe(
+    Effect.flatMap(
+      transactionId =>
+        makeEndpoint('PUT', {
+          auth: true,
+          schema,
+          body: RequestOptions.body(messageContentSchema, options.content),
+        })`/v3/rooms/${RequestOptions.path(
+          RoomId.schema,
+          options.roomId,
+        )}/send/${RequestOptions.path(eventTypeSchema, options.eventType)}/${RequestOptions.path(Schema.String, transactionId)}`,
+    ),
+  )
diff --git a/packages/mxfx/src/api/endpoints/sync/get-sync-v3.ts b/packages/mxfx/src/api/endpoints/sync/get-sync-v3.ts
index 8d619f6..efd3d4b 100644
--- a/packages/mxfx/src/api/endpoints/sync/get-sync-v3.ts
+++ b/packages/mxfx/src/api/endpoints/sync/get-sync-v3.ts
@@ -1,15 +1,15 @@
-import { Effect, Schema } from 'effect'
+import { Schema } from 'effect'
 
 import { EventId, RoomId } from '../../../branded/index.ts'
 import { baseEvent, strippedStateEvent, filterSchema } from '../../../schema/index.ts'
-import { encodeSnakeCaseSchema } from '../../schema/encode-case.ts'
 import { AccountData, StateSchema, Timeline } from '../../schema/sync.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const presenceSchema = Schema.Union([Schema.Literal('online'), Schema.Literal('offline'), Schema.Literal('unavailable')])
 
 const optionsSchema = Schema.Struct({
-  filter: Schema.optional(Schema.fromJsonString(encodeSnakeCaseSchema(filterSchema))), //TODO: remove snakecase handling here
+  filter: Schema.optional(Schema.fromJsonString(filterSchema)),
   fullState: Schema.optional(Schema.Boolean),
   setPresence: Schema.optional(presenceSchema),
   since: Schema.optional(Schema.String),
@@ -105,8 +105,4 @@ const schema = getSyncV3ResponseSchema
  * @see https://spec.matrix.org/v1.17/client-server-api/#get_matrixclientv3sync
  */
 export const getSyncV3 = (options: typeof optionsSchema.Type) =>
-  Effect.gen(function* () {
-    const params = yield* Schema.encodeEffect(encodeSnakeCaseSchema(optionsSchema))(options) //TODO: remove snakecase handling here
-
-    return yield* makeEndpoint('GET', { auth: true, params, schema })`/v3/sync`
-  })
+  makeEndpoint('GET', { auth: true, query: RequestOptions.query(optionsSchema, options), schema })`/v3/sync`
diff --git a/packages/mxfx/src/api/endpoints/user-directory/post-user-directory-search-v3.ts b/packages/mxfx/src/api/endpoints/user-directory/post-user-directory-search-v3.ts
index 37e1fc7..c06dc37 100644
--- a/packages/mxfx/src/api/endpoints/user-directory/post-user-directory-search-v3.ts
+++ b/packages/mxfx/src/api/endpoints/user-directory/post-user-directory-search-v3.ts
@@ -1,9 +1,8 @@
-import { Effect, Schema } from 'effect'
-import { HttpBody } from 'effect/unstable/http'
+import { Schema } from 'effect'
 
 import { MxcUri } from '../../../branded/index.ts'
-import { encodeSnakeCaseSchema } from '../../schema/encode-case.ts'
 import { makeEndpoint } from '../endpoint.ts'
+import * as RequestOptions from '../request-options.ts'
 
 const optionsSchema = Schema.Struct({
   limit: Schema.optional(Schema.Int),
@@ -31,8 +30,4 @@ const schema = Schema.Struct({
  * @see https://spec.matrix.org/v1.17/client-server-api/#post_matrixclientv3user_directorysearch
  */
 export const postUserDirectorySearchV3 = (options: Schema.Schema.Type<typeof optionsSchema>) =>
-  Effect.gen(function* () {
-    const body = yield* Schema.encodeEffect(optionsSchema.pipe(encodeSnakeCaseSchema))(options).pipe(Effect.andThen(HttpBody.json))
-
-    return yield* makeEndpoint('POST', { auth: true, body, schema })`/v3/user_directory/search`
-  })
+  makeEndpoint('POST', { auth: true, body: RequestOptions.body(optionsSchema, options), schema })`/v3/user_directory/search`
diff --git a/packages/mxfx/src/api/schema/encode-case.ts b/packages/mxfx/src/api/schema/encode-case.ts
index bac7c83..b0db6b4 100644
--- a/packages/mxfx/src/api/schema/encode-case.ts
+++ b/packages/mxfx/src/api/schema/encode-case.ts
@@ -29,6 +29,15 @@ type AnyOptionalWrapper = AnyWrapper & {
     readonly members: ReadonlyArray<Schema.Top>
   }
 }
+type AnyFromJsonString = {
+  readonly from: {
+    readonly ast: {
+      readonly _tag: 'String'
+      readonly annotations?: { readonly contentMediaType?: string }
+    }
+  }
+  readonly to: Schema.Top
+}
 
 const isSchemaLike = (value: unknown): value is object | Function =>
   (typeof value === 'object' || typeof value === 'function') && value !== null
@@ -49,6 +58,13 @@ const isOptionalWrapperSchema = (value: unknown): value is AnyOptionalWrapper =>
   (value as AnyOptionalWrapper).schema !== null &&
   'members' in (value as AnyOptionalWrapper).schema &&
   (value as AnyOptionalWrapper).schema.members.some(member => member.ast._tag === 'Undefined')
+const isFromJsonStringSchema = (value: unknown): value is AnyFromJsonString =>
+  isSchemaLike(value) &&
+  'from' in value &&
+  'to' in value &&
+  isSchemaLike((value as AnyFromJsonString).from) &&
+  (value as AnyFromJsonString).from.ast._tag === 'String' &&
+  (value as AnyFromJsonString).from.ast.annotations?.contentMediaType === 'application/json'
 
 const encodeSnakeCaseStruct = (schema: AnyStruct): Schema.Top => {
   const nestedFields = Object.fromEntries(
@@ -85,6 +101,10 @@ const encodeSnakeCaseSchemaInternal = (schema: Schema.Top): Schema.Top => {
     return member ? Schema.optional(encodeSnakeCaseSchemaInternal(member)) : schema
   }
 
+  if (isFromJsonStringSchema(schema)) {
+    return Schema.fromJsonString(encodeSnakeCaseSchemaInternal(schema.to))
+  }
+
   return schema
 }