How to use the Anthropic plugin

Call Claude models from Kestra flows for text generation, summarization, classification, and other language tasks.

Authentication

Set apiKey to your Anthropic API key. Store it in a secret.

Tasks

ChatCompletion sends a prompt to a Claude model and returns the response. Set model to choose the model (e.g., claude-opus-4-7, claude-sonnet-4-6) and maxTokens to cap the response length. It returns the completion text, any tool uses, the stop reason, and cache-token counts as outputs, and emits input/output/cache token-usage metrics.

CountTokens estimates input tokens for the same messages, system, tools, and model you would send to ChatCompletion. It calls the token-count endpoint and returns inputTokens only. It does not create a message or call the model. A later task can read {{ outputs.count_tokens.inputTokens }} and skip ChatCompletion when the count is too high.

MessageBatch creates, retrieves, or cancels an Anthropic Message Batch. Set mode to CREATE and pass requests (each with a unique customId, a model, and messages) to start a batch and return batchId. customId is letters, digits, _, or -, 1–64 characters, and is sent unchanged. Set mode to RETRIEVE with that batchId to read status and requestCounts. Once status is ended, the same call also returns resultsUrl. By default fetchType is STORE: per-request rows are written to Kestra internal storage as an ION file (uri, with size) instead of being kept on the task output. Set fetchType to FETCH to return every row on results, FETCH_ONE for the first row only, or NONE to skip the download. If the results file is no longer available, RETRIEVE still returns the batch status and logs a warning. Repeat RETRIEVE from a LoopUntil task until the batch ends, and set retry on that task for transient download errors. CANCEL stops a batch that is still processing. Batches run asynchronously (at most 24 hours) and are billed at half the real-time Messages API rate. RETRIEVE emits one total per token-usage metric for the succeeded rows it actually read.

ListModels lists the Claude models available to your API key.

The Files API tasks manage files for use with Claude, all via Anthropic's beta Files endpoint: UploadFile uploads a file from Kestra internal storage, GetFile retrieves a file's metadata, ListFiles lists stored files, and DeleteFile removes one.