additionalProperties is boolean

[lp2jx0309]

additionalProperties is boolean for java-sdk
io.modelcontextprotocol.spec.McpSchema.JsonSchema

[jba]

This keyword has always been a schema in the spec.
https://json-schema.org/draft-07/draft-handrews-json-schema-validation-01#rfc.section.6.5.6
https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-01#name-additionalproperties

[rdejana]

Is there a reason for not following what the Java SDK (and from what I'm seeing the Python SDK as well) does? I've noticed that some clients assume that this field will be a boolean. I know this isn't necessarily an issue with the Go code, I'm just curious.

[findleyr]

@jba I think additionalProperties can either be a schema, or the keyword false.
https://json-schema.org/understanding-json-schema/reference/object#additionalproperties

[jba]

Is there a reason for not following what the Java SDK (and from what I'm seeing the Python SDK as well) does?

Yes: they don't implement the JSON Schema spec, and we do.

The JSON true is shorthand for {}, the empty schema, which validates everything.
The JSON false is shorthand for {"not": {}}, which validates nothing.

Our package doesn't support true and false directly, because then every *Schema would become an any.

Is your problem that you are having difficulty constructing the schema you want in Go? In that case, you can use this function:

func falseSchema() *Schema {
  return &Schema{Not: &Schema{}}
}

Is the problem that LLMs don't understand {} and {"not": {}}? Then they have a bug. But since it's infeasible to fix all of them, we could provide some sort of option that JSON-marshals {} to true and {"not": {}} to false.

[jba]

Or is the problem that we receive JSON with "additionalProperties": false? Then we can special-case that in Schema.UnmarshalJSON. Which we already do.

[Aavishkar-Kolte]

Is there a reason for not following what the Java SDK (and from what I'm seeing the Python SDK as well) does? I've noticed that some clients assume that this field will be a boolean. I know this isn't necessarily an issue with the Go code, I'm just curious.

True, I was trying to add go-sdk examples to the LM Studio desktop app. and I was getting a similar error where LM Studio was expecting "additionalProperties," a boolean, but instead got an object. It would be great if the SDK could provide a feature to marshal to true/false instead of {} and {"not": {}}.

[jba]

I filed #244. Those ideas aren't enough, though; we have to make sure the choice to marshal as bools makes it into to ListTools.

LM studios has no public repos (https://github.com/lmstudio) so I don't know where to file a bug against them. Someone needs to tell them that their JSON Schema implementation is wrong.

[Aavishkar-Kolte]

I filed #244. Those ideas aren't enough, though; we have to make sure the choice to marshal as bools makes it into to ListTools.

LM studios has no public repos (https://github.com/lmstudio) so I don't know where to file a bug against them. Someone needs to tell them that their JSON Schema implementation is wrong.

Thanks @jba!
LM studios has a bug-tracker repo https://github.com/lmstudio-ai/lmstudio-bug-tracker where we can file bugs.
I have already filled a bug(lmstudio-ai/lmstudio-bug-tracker#852) on this particular issue.