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A call to a custom (freeform-grammar) tool created by the model — distinct from function_call. Used for tools like Codex CLI’s apply_patch whose payload is opaque text rather than JSON arguments.

Fields

FieldTypeRequiredDescription
call_idstr:heavy_check_mark:N/A
idOptional[str]:heavy_minus_sign:N/A
inputstr:heavy_check_mark:N/A
namestr:heavy_check_mark:N/A
namespaceOptional[str]:heavy_minus_sign:Namespace qualifier for tools registered as part of a namespace tool group (e.g. an MCP server)
typecomponents.OutputCustomToolCallItemType:heavy_check_mark:N/A