anthropic-sdk-clj

An idiomatic Clojure wrapper over the official Anthropic Java SDK (com.anthropic/anthropic-java). Build a request as a Clojure map, get a Clojure map back.

Stack

Why

Every other Clojure Anthropic library hand-rolls HTTP against the REST API, which means each one is perpetually chasing Anthropic's surface and tends to fall behind. This one wraps Anthropic's own actively-maintained Java SDK instead, so streaming, tool use, retries, and every new model and feature arrive the moment Anthropic ships them in Java - you just get a Clojure-shaped API on top: maps in, maps out, keywords for roles and block types.

Install

Leiningen (project.clj):

[net.clojars.savya/anthropic-sdk-clj "0.1.0"]

tools.deps (deps.edn):

net.clojars.savya/anthropic-sdk-clj {:mvn/version "0.1.0"}

Set ANTHROPIC_API_KEY in your environment (or pass :api-key to client).

Usage

(require '[anthropic.core :as anthropic])

(def client (anthropic/client))   ; reads ANTHROPIC_API_KEY

;; A single message. :model defaults to "claude-opus-4-8", :max-tokens to 1024.
(anthropic/create-message
  client
  {:model "claude-opus-4-8"
   :max-tokens 1024
   :system "You are concise."
   :messages [{:role :user :content "Name three primary colors."}]})
;; => {:id "msg_..." :model "claude-opus-4-8" :role :assistant
;;     :stop-reason :end-turn
;;     :content [{:type :text :text "Red, blue, yellow."}]
;;     :usage {:input-tokens 18 :output-tokens 9}}

Streaming

stream-text calls your callback with each text delta and returns the full text.

(anthropic/stream-text
  client
  {:model "claude-opus-4-8" :max-tokens 256
   :messages [{:role :user :content "Write a haiku about parentheses."}]}
  #(print %))   ; prints each delta as it arrives
;; => returns the complete string when the stream ends

Tool use

Declare tools as maps; tool_use blocks come back parsed, and you complete the loop by echoing the assistant turn and sending a :tool-result block.

(def weather-tool
  {:name "get_weather"
   :description "Get the current weather for a city"
   :input-schema {:type "object"
                  :properties {:city {:type "string"}}
                  :required ["city"]}})

(def ask {:role :user :content "What's the weather in Paris?"})

(def r1 (anthropic/create-message
          client {:tools [weather-tool] :messages [ask]}))

;; r1 :stop-reason is :tool-use; find the call:
(def call (first (filter #(= :tool-use (:type %)) (:content r1))))
;; => {:type :tool-use :id "toolu_..." :name "get_weather" :input {:city "Paris"}}

;; Run the tool yourself, then send the result back:
(anthropic/create-message
  client
  {:tools [weather-tool]
   :messages [ask
              {:role :assistant :content (:content r1)}
              {:role :user :content [{:type :tool-result
                                      :tool-use-id (:id call)
                                      :content "18°C and sunny"}]}]})
;; => {... :content [{:type :text :text "It's 18°C and sunny in Paris."}]}

What's covered

• create-message - request map ↔ response map
• stream-text - incremental text deltas
• Tool use - tools, parsed tool_use blocks, tool_result round-trip
• Roadmap (0.2): structured outputs (output_config.format), batches, files

Tests

Unit tests (the request/response translation) run with no network:

lein test

The :integration suite hits the live API and is billed - it needs ANTHROPIC_API_KEY and is run explicitly:

ANTHROPIC_API_KEY=sk-... lein test :integration

License

Copyright © 2026 Savyasachi

Distributed under the Eclipse Public License 2.0. The wrapped com.anthropic/anthropic-java SDK is MIT-licensed and remains the property of Anthropic.