fix(client) add encodeDefault for field with non spec default value #99

shiqicao · 2025-05-05T19:27:07Z

type in Tool.Input has a default value, but the spec doesn't treat it as default value, therefore serailizer should always write it.

Motivation and Context

Serialized Tool can be used directly in calling anthropic api (without SDK).

How Has This Been Tested?

Passing all existing tests

Breaking Changes

It is a breaking change if code depends on "missing" type behavior

Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)
Documentation update

Checklist

I have read the MCP Documentation
My code follows the repository's style guidelines
New and existing tests pass locally
I have added appropriate error handling
I have added or updated documentation as needed

Additional context

Copilot

Pull Request Overview

This PR fixes a bug by ensuring that the "type" field in Tool.Input is always written during serialization even when it matches the default value, in accordance with the spec.

Key changes include adding @EncodeDefault and @OptIn(ExperimentalSerializationApi) annotations for the "type" property.
The file affected is updated to enforce the correct serialization behavior for the "type" field.

Copilot · 2025-05-06T06:36:06Z

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt

@@ -1050,6 +1052,8 @@ public data class Tool(
        val properties: JsonObject = EmptyJsonObject,
        val required: List<String>? = null,
    ) {
+        @OptIn(ExperimentalSerializationApi::class)


[nitpick] Consider adding an inline comment explaining the necessity of @EncodeDefault here, linking it to the spec requirement that the 'type' field must always be serialized.

Suggested change

@OptIn(ExperimentalSerializationApi::class)

@OptIn(ExperimentalSerializationApi::class)

// The @EncodeDefault annotation ensures that the 'type' field is always serialized,

// as required by the specification for JSON schema objects.

e5l

Hey @shiqicao! Thanks for the PR. Could you add a unit test so I can merge?

| Package | Type | Package file | Manager | Update | Change | |---|---|---|---|---|---| | [io.modelcontextprotocol:kotlin-sdk](https://github.com/modelcontextprotocol/kotlin-sdk) | dependencies | misk/gradle/libs.versions.toml | gradle | minor | `0.5.0` -> `0.6.0` | | [org.jetbrains.kotlinx:kotlinx-serialization-json](https://github.com/Kotlin/kotlinx.serialization) | dependencies | misk/gradle/libs.versions.toml | gradle | minor | `1.7.3` -> `1.9.0` | | [org.jetbrains.kotlinx:kotlinx-serialization-core](https://github.com/Kotlin/kotlinx.serialization) | dependencies | misk/gradle/libs.versions.toml | gradle | minor | `1.7.3` -> `1.9.0` | | [com.google.apis:google-api-services-storage](http://nexus.sonatype.org/oss-repository-hosting.html) ([source](http://svn.sonatype.org/spice/tags/oss-parent-7)) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `v1-rev20250718-2.0.0` -> `v1-rev20250814-2.0.0` | | [software.amazon.awssdk:sdk-core](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | | [software.amazon.awssdk:sqs](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | | [software.amazon.awssdk:regions](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | | [software.amazon.awssdk:dynamodb-enhanced](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | | [software.amazon.awssdk:dynamodb](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | | [software.amazon.awssdk:aws-core](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | | [software.amazon.awssdk:bom](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | | [software.amazon.awssdk:auth](https://aws.amazon.com/sdkforjava) | dependencies | misk/gradle/libs.versions.toml | gradle | patch | `2.32.23` -> `2.32.24` | --- ### Release Notes <details> <summary>modelcontextprotocol/kotlin-sdk (io.modelcontextprotocol:kotlin-sdk)</summary> ### [`v0.6.0`](https://github.com/modelcontextprotocol/kotlin-sdk/releases/tag/0.6.0) [Compare Source](modelcontextprotocol/kotlin-sdk@0.5.0...0.6.0) #### What's Changed - Update jreleaser to fix publication issue by [@e5l](https://github.com/e5l) in modelcontextprotocol/kotlin-sdk#91 - Disable configuration cache to fix jreleaser issue by [@e5l](https://github.com/e5l) in modelcontextprotocol/kotlin-sdk#92 - feat: Add audio type according to 2025-03-26 spec by [@SeanChinJunKai](https://github.com/SeanChinJunKai) in modelcontextprotocol/kotlin-sdk#68 - fix(client): serialize inputSchema as input\_schema by [@shiqicao](https://github.com/shiqicao) in modelcontextprotocol/kotlin-sdk#97 - fix(client) add encodeDefault for field with non spec default value by [@shiqicao](https://github.com/shiqicao) in modelcontextprotocol/kotlin-sdk#99 - Make McpJson public to allow flexible protocol development by [@parnurzeal](https://github.com/parnurzeal) in modelcontextprotocol/kotlin-sdk#103 - fix: apply `requestBuilder` headers when sending rpc messages by [@dead8309](https://github.com/dead8309) in modelcontextprotocol/kotlin-sdk#96 - fix: Remove [@SerialName](https://github.com/SerialName) annotation for inputSchema by [@adamglin0](https://github.com/adamglin0) in modelcontextprotocol/kotlin-sdk#105 - add ios and wasm targets by [@devcrocod](https://github.com/devcrocod) in modelcontextprotocol/kotlin-sdk#81 - Add dependabot by [@StefMa](https://github.com/StefMa) in modelcontextprotocol/kotlin-sdk#121 - Bump org.jetbrains.kotlinx:kotlinx-serialization-json from 1.7.3 to 1.8.1 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#127 - Bump io.github.oshai:kotlin-logging from 7.0.0 to 7.0.7 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#126 - Bump org.jetbrains.kotlinx.binary-compatibility-validator from 0.17.0 to 0.18.0 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#125 - update kotlin to 2.2.0 and ktor to 3.1.3 by [@devcrocod](https://github.com/devcrocod) in modelcontextprotocol/kotlin-sdk#120 - Add client roots addition/removal API and listRoots handler by [@ptitjes](https://github.com/ptitjes) in modelcontextprotocol/kotlin-sdk#118 - Bump org.slf4j:slf4j-simple from 2.0.16 to 2.0.17 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#131 - Bump org.jetbrains.kotlinx:kotlinx-serialization-json from 1.8.1 to 1.9.0 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#132 - Bump io.mockk:mockk from 1.13.13 to 1.14.4 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#133 - Remove fixed suffix /sse by [@adamglin0](https://github.com/adamglin0) in modelcontextprotocol/kotlin-sdk#108 - sse server does not process endpoint correctly when sse path is not a directory by [@shendaxia-sm](https://github.com/shendaxia-sm) in modelcontextprotocol/kotlin-sdk#43 - Add labels to dependabot configuration for Kotlin and GitHub Actions by [@devcrocod](https://github.com/devcrocod) in modelcontextprotocol/kotlin-sdk#135 - feat: add tool annotations according to 2025-03-26 spec by [@SeanChinJunKai](https://github.com/SeanChinJunKai) in modelcontextprotocol/kotlin-sdk#71 - Bump ktor from 3.1.3 to 3.2.1 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#140 - Bump gradle/actions from 4.0.0 to 4.4.1 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#122 - Bump org.jreleaser from 1.17.0 to 1.19.0 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#141 - refactor `SseClientTransport` by [@devcrocod](https://github.com/devcrocod) in modelcontextprotocol/kotlin-sdk#142 - atomic and persistent collections for thread safety by [@devcrocod](https://github.com/devcrocod) in modelcontextprotocol/kotlin-sdk#143 - Bump org.gradle.toolchains.foojay-resolver-convention from 0.8.0 to 1.0.0 by [@dependabot](https://github.com/dependabot)\[bot] in modelcontextprotocol/kotlin-sdk#130 - Add support for elicitation by [@ptitjes](https://github.com/ptitjes) in modelcontextprotocol/kotlin-sdk#138 - Add support for tool structured content and output schema by [@ptitjes](https://github.com/ptitjes) in modelcontextprotocol/kotlin-sdk#146 - Add streamable http client transport by [@devcrocod](https://github.com/devcrocod) in modelcontextprotocol/kotlin-sdk#147 - Refactor JSON processing to exclude "method" in serialization by [@devcrocod](https://github.com/devcrocod) in [#157](modelcontextprotocol/kotlin-sdk#157) - Release 0.6.0 by [@devcrocod](https://github.com/devcrocod) in modelcontextprotocol/kotlin-sdk#149 #### New Contributors - [@shiqicao](https://github.com/shiqicao) made their first contribution in modelcontextprotocol/kotlin-sdk#97 - [@parnurzeal](https://github.com/parnurzeal) made their first contribution in modelcontextprotocol/kotlin-sdk#103 - [@dead8309](https://github.com/dead8309) made their first contribution in modelcontextprotocol/kotlin-sdk#96 - [@adamglin0](https://github.com/adamglin0) made their first contribution in modelcontextprotocol/kotlin-sdk#105 - [@StefMa](https://github.com/StefMa) made their first contribution in modelcontextprotocol/kotlin-sdk#121 - [@dependabot](https://github.com/dependabot)\[bot] made their first contribution in modelcontextprotocol/kotlin-sdk#127 - [@ptitjes](https://github.com/ptitjes) made their first contribution in modelcontextprotocol/kotlin-sdk#118 - [@shendaxia-sm](https://github.com/shendaxia-sm) made their first contribution in modelcontextprotocol/kotlin-sdk#43 **Full Changelog**: modelcontextprotocol/kotlin-sdk@0.5.0...0.6.0 </details> <details> <summary>Kotlin/kotlinx.serialization (org.jetbrains.kotlinx:kotlinx-serialization-json)</summary> ### [`v1.9.0`](https://github.com/Kotlin/kotlinx.serialization/blob/HEAD/CHANGELOG.md#190--2025-06-27) \================== This release updates Kotlin version to 2.2.0, includes several bugfixes and provides serializers for kotlin.time.Instant. #### Add kotlin.time.Instant serializers Instant class was moved from kotlinx-datetime library to Kotlin standard library. As a result, kotlinx-datetime 0.7.0 no longer has serializers for the Instant class. To use new kotlin.time.Instant class in your [@Serializable](https://github.com/Serializable) classes, you can use this 1.9.0 kotlinx-serialization version (Kotlin 2.2 is required). You can choose between default `InstantSerializer` which uses its string representation, or specify `InstantComponentSerializer` that represents instant as its components. See details in the [PR](Kotlin/kotlinx.serialization#2945). #### Other bugfixes - Fix resize in JsonPath ([#2995](Kotlin/kotlinx.serialization#2995)) - Fixed proguard rules for obfuscation to work correctly ([#2983](Kotlin/kotlinx.serialization#2983)) ### [`v1.8.1`](https://github.com/Kotlin/kotlinx.serialization/blob/HEAD/CHANGELOG.md#181--2025-03-31) \================== This release updates Kotlin version to 2.1.20, while also providing several important improvements and bugfixes. #### Improvements - Implemented encoding null in key and value of a map in Protobuf ([#2910](Kotlin/kotlinx.serialization#2910)) - Make type argument in JsonTransformingSerializer nullable ([#2911](Kotlin/kotlinx.serialization#2911)) - Use SPDX identifier in POMs ([#2936](Kotlin/kotlinx.serialization#2936)) (thanks to [Leon Linhart](https://github.com/TheMrMilchmann)) - Add watchosDeviceArm64 to Okio integration module ([#2920](Kotlin/kotlinx.serialization#2920)) (thanks to [Daniel Santiago](https://github.com/danysantiago)) - Update kotlinx-io version to 0.6.0 ([#2933](Kotlin/kotlinx.serialization#2933)) (thanks to [Piotr Krzemiński](https://github.com/krzema12)) #### Bugfixes - Fix incorrect enum coercion during deserialization from JsonElement ([#2962](Kotlin/kotlinx.serialization#2962)) - Supply proper equals(), hashCode(), and toString() for SerialDescriptor() wrapper ([#2942](Kotlin/kotlinx.serialization#2942)) - Do not encode empty packed collections in protobuf ([#2907](Kotlin/kotlinx.serialization#2907)) ### [`v1.8.0`](https://github.com/Kotlin/kotlinx.serialization/blob/HEAD/CHANGELOG.md#180--2025-01-06) \================== This release contains all of the changes from 1.8.0-RC. Kotlin 2.1.0 is used as a default, while upcoming 2.1.10 is also supported. Also added small bugfixes, including speedup of ProtoWireType.from ([#2879](Kotlin/kotlinx.serialization#2879)). </details> --- ### Configuration 📅 **Schedule**: Branch creation - "after 6pm every weekday,before 2am every weekday" in timezone Australia/Melbourne, Automerge - At any time (no schedule defined). 🚦 **Automerge**: Enabled. ♻ **Rebasing**: Never, or you tick the rebase/retry checkbox. 👻 **Immortal**: This PR will be recreated if closed unmerged. Get [config help](https://github.com/renovatebot/renovate/discussions) if that's undesired. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate). GitOrigin-RevId: 40e2f07ecd958e92e64c571d1351e91f96e71ce7

e5l requested review from e5l and Copilot and removed request for e5l May 6, 2025 06:35

Copilot AI reviewed May 6, 2025

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e5l requested changes May 6, 2025

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fix(client) add encodeDefault for field with non spec default value

b23faa6

shiqicao force-pushed the fix_default_serialization branch from dc9873a to f7347c8 Compare May 6, 2025 22:08

add test

98d8de7

shiqicao force-pushed the fix_default_serialization branch from f7347c8 to 98d8de7 Compare May 6, 2025 22:23

e5l approved these changes May 9, 2025

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e5l enabled auto-merge (squash) May 9, 2025 06:51

e5l merged commit fb568bb into modelcontextprotocol:main May 9, 2025
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fix(client) add encodeDefault for field with non spec default value #99

fix(client) add encodeDefault for field with non spec default value #99

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shiqicao commented May 5, 2025

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fix(client) add encodeDefault for field with non spec default value #99

fix(client) add encodeDefault for field with non spec default value #99

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shiqicao commented May 5, 2025

Motivation and Context

How Has This Been Tested?

Breaking Changes

Types of changes

Checklist

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Copilot AI May 6, 2025

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