Info: MiMo parser returns string when tool param has no type (anyOf-only)

[yanyihan-xiaomi]

Behavior (not a mimocode bug)

MiMo models / inference parser have a fixed behavior on tool-call top-level (or nested) parameters:

• If the schema node has no explicit type (e.g. only anyOf / union arms), the parser returns a string for that field instead of a structured object.

This is not something mimocode needs to “fix” in the model or wire format.

What mimocode should do

Handle a string payload correctly at the tool boundary:

• If the tool expects an object, accept object | string
• When it is a string, JSON.parse (or equivalent) then validate with the same schema
• Do not teach the model in prompts/errors that “string is allowed” — that is a parser-side phenomenon

Desktop tts_speech.voice already does this (parseMaybeString + zod). Same pattern applies to any nested union tool arg.

Closed

Documenting behavior only; no engine work tracked here.

[yanyihan-xiaomi]

Closing — not needed. Desktop treats stringified nested voice as a durable execute contract; no engine tracking issue required.