LLM Provider Message Migration Kit

Convert submitted message and tool-call fixtures between OpenAI, Anthropic, Gemini, and canonical Utilito shapes without a model rewrite.

AI builders migrating deterministic message fixtures, tools, and tool results between provider APIs.

Source providerTarget provider

Submitted source messages (strict JSON array)Submitted source tool definitions (strict JSON array)Unsupported-field policy

Only the documented bounded provider subset is converted. Credentials, unknown providers, malformed tool arguments, unresolved tool results, and unsupported object shapes fail closed. Nothing is sent to a provider.

The visible sample was built through the deterministic migration core during this static build. Rebuild the current input to enable copy and downloads.

Converted provider payload

{
  "system": [
    {
      "type": "text",
      "text": "Keep submitted content exact."
    }
  ],
  "messages": [
    {
      "role": "user",
      "content": "Weather for Paris?"
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "tool_use",
          "id": "call_weather_1",
          "name": "weather",
          "input": {
            "city": "Paris"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "call_weather_1",
          "content": "{\"temperature\":21}"
        }
      ]
    }
  ],
  "tools": [
    {
      "name": "weather",
      "description": "Read a submitted weather fixture.",
      "input_schema": {
        "additionalProperties": false,
        "properties": {
          "city": {
            "type": "string"
          }
        },
        "required": [
          "city"
        ],
        "type": "object"
      }
    }
  ]
}

Unsupported-field diagnostics

[
  {
    "code": "SYSTEM_ROLE_LOCATION",
    "path": "messages[0].role",
    "message": "The target represents the system instruction outside its ordinary message array.",
    "disposition": "remapped"
  }
]

Role and tool-call mapping

[
  {
    "source_index": 0,
    "source_role": "system",
    "canonical_role": "system",
    "target_role": "system",
    "tool_calls": []
  },
  {
    "source_index": 1,
    "source_role": "user",
    "canonical_role": "user",
    "target_role": "user",
    "tool_calls": []
  },
  {
    "source_index": 2,
    "source_role": "assistant",
    "canonical_role": "assistant",
    "target_role": "assistant",
    "tool_calls": [
      {
        "source_id": "call_weather_1",
        "target_id": "call_weather_1",
        "status": "preserved"
      }
    ]
  },
  {
    "source_index": 3,
    "source_role": "tool",
    "canonical_role": "tool",
    "target_role": "user",
    "tool_calls": []
  }
]

Complete migration envelope

{
  "ok": true,
  "schema_version": "utilito.product-kit.v1",
  "kit": {
    "id": "provider-message-migration-kit",
    "version": "1.0.0"
  },
  "result": {
    "source_provider": "openai",
    "target_provider": "anthropic",
    "unsupported_field_policy": "diagnose",
    "converted_payload": {
      "system": [
        {
          "type": "text",
          "text": "Keep submitted content exact."
        }
      ],
      "messages": [
        {
          "role": "user",
          "content": "Weather for Paris?"
        },
        {
          "role": "assistant",
          "content": [
            {
              "type": "tool_use",
              "id": "call_weather_1",
              "name": "weather",
              "input": {
                "city": "Paris"
              }
            }
          ]
        },
        {
          "role": "user",
          "content": [
            {
              "type": "tool_result",
              "tool_use_id": "call_weather_1",
              "content": "{\"temperature\":21}"
            }
          ]
        }
      ],
      "tools": [
        {
          "name": "weather",
          "description": "Read a submitted weather fixture.",
          "input_schema": {
            "additionalProperties": false,
            "properties": {
              "city": {
                "type": "string"
              }
            },
            "required": [
              "city"
            ],
            "type": "object"
          }
        }
      ]
    },
    "unsupported_diagnostics": [
      {
        "code": "SYSTEM_ROLE_LOCATION",
        "path": "messages[0].role",
        "message": "The target represents the system instruction outside its ordinary message array.",
        "disposition": "remapped"
      }
    ],
    "role_tool_call_mapping": [
      {
        "source_index": 0,
        "source_role": "system",
        "canonical_role": "system",
        "target_role": "system",
        "tool_calls": []
      },
      {
        "source_index": 1,
        "source_role": "user",
        "canonical_role": "user",
        "target_role": "user",
        "tool_calls": []
      },
      {
        "source_index": 2,
        "source_role": "assistant",
        "canonical_role": "assistant",
        "target_role": "assistant",
        "tool_calls": [
          {
            "source_id": "call_weather_1",
            "target_id": "call_weather_1",
            "status": "preserved"
          }
        ]
      },
      {
        "source_index": 3,
        "source_role": "tool",
        "canonical_role": "tool",
        "target_role": "user",
        "tool_calls": []
      }
    ],
    "canonical_intermediate": {
      "schema_version": "utilito.provider-message.v1",
      "source_provider": "openai",
      "messages": [
        {
          "role": "system",
          "content": "Keep submitted content exact.",
          "tool_calls": []
        },
        {
          "role": "user",
          "content": "Weather for Paris?",
          "tool_calls": []
        },
        {
          "role": "assistant",
          "content": "",
          "tool_calls": [
            {
              "id": "call_weather_1",
              "name": "weather",
              "arguments": {
                "city": "Paris"
              },
              "arguments_json": "{\"city\":\"Paris\"}",
              "source_call_index": 0
            }
          ]
        },
        {
          "role": "tool",
          "content": "{\"temperature\":21}",
          "tool_call_id": "call_weather_1",
          "tool_name": "weather",
          "tool_calls": []
        }
      ],
      "tools": [
        {
          "name": "weather",
          "description": "Read a submitted weather fixture.",
          "parameters": {
            "additionalProperties": false,
            "properties": {
              "city": {
                "type": "string"
              }
            },
            "required": [
              "city"
            ],
            "type": "object"
          }
        }
      ]
    }
  },
  "receipt": {
    "input_bytes": 683,
    "output_bytes": 2729,
    "operations": 3,
    "omitted_items": 0,
    "warnings": [
      "SYSTEM_ROLE_LOCATION"
    ],
    "messages": 4,
    "tools": 1,
    "diagnostics": 1,
    "tool_call_ids_preserved": 1,
    "tool_call_ids_remapped": 0,
    "values_invented": 0
  },
  "provenance": {
    "deterministic": true,
    "model_used": false,
    "network_used": false,
    "storage_used": false,
    "core_versions": {
      "provider_message_migration_kit": "1.0.0",
      "message_json": "message-json-core"
    }
  },
  "error": null
}

Download converted payload Download migration envelope

Free runnable capability

Convert one bounded fixture locally and download the current JSON envelope with no signup.

Builder capability

The existing Builder Pilot can coordinate bounded fixture-suite batches; it does not add provider calls, credentials, model rewriting, storage, or hidden retries.

See the existing Builder Pilot

Privacy boundary

Browser conversion runs locally with deterministic message adapters. API and MCP requests are response-only; no provider call, credential, arbitrary URL, model, network, storage, or telemetry is accepted or used.

Limits and trust boundary

Only the documented bounded message, text, tool-call, tool-result, and function-definition subset is converted. Provider-specific multimodal, cache, reasoning, safety, streaming, and transport fields are not inferred.
System and developer semantics differ by provider. Every preserved or remapped role and every non-representable or generated tool-call ID is exposed in diagnostics and the mapping table.
Tool arguments must already be valid JSON objects. Content, arguments, results, and tool schemas are never rewritten, summarized, coerced, or completed by a model.
Credentials and credential-bearing fields are rejected. The kit never calls a provider, accepts arbitrary URLs, stores fixtures, emits payload telemetry, or sends converted payloads.