API tutorial
Claude Fable 5.2 API Quickstart with the Messages API
If you are connecting Fable 5.2 to a review pipeline, start with a small request whose result you can inspect. We followed Anthropic's Claude API reference and model notes for this quickstart. The example uses the first-party endpoint and a fictional brief.
The quick steps
Set your Claude API credential outside the code, call the Messages endpoint with model ID claude-fable-5-2, then inspect the returned text blocks, stop reason and usage. Add an image or tools after the minimal request works.
1. Prepare access and a small test input
Use a Claude Platform API key and make it available as the ANTHROPIC_API_KEY environment variable in your local shell. Use a fictional brief while you validate the integration. The key belongs in your credential store and should stay out of the request logs.
2. Send the first message
Copy this example into a shell that has the key. The request asks for a short list of missing inputs. The output may contain multiple content blocks, so check types when you extract text.
curl https://api.anthropic.com/v1/messages \
-H "x-api-key: $ANTHROPIC_API_KEY" \
-H "anthropic-version: 2023-06-01" \
-H "content-type: application/json" \
-d '{"model":"claude-fable-5-2","max_tokens":1024,"messages":[{"role":"user","content":"A fictional bakery needs a launch graphic. List three details to confirm before writing a design brief."}]}'3. Inspect the actual response
Read the text blocks and check the stop reason. A maximum-token stop calls for a tighter request or a revised budget. Log model ID and token usage beside a request identifier, then compare the usage with the direct API rate.
4. Add one capability at a time
After the text request succeeds, attach one image using the documented vision request shape and validate the response against a known label. Add tools after that. Fable 5.2 uses adaptive thinking and the model documentation calls out unsupported forced tool-choice options and certain sampling settings. Keep the first request free of those options.
5. Keep the handoff readable
For a design pipeline, produce a short brief containing source IDs, required copy and unknowns. Have a person verify it before copying the approved brief to Ciyo for visual work. Save the accepted result and the source image IDs so a later revision can reconstruct the decision.
Diagnose a small request before adding a pipeline
An authentication failure calls for checking the selected credential and organization; a request-shape error calls for reading the returned error and the model notes. Keep the two cases separate. Record the status, request identifier and a redacted message rather than copying the credential into a support note.
For a response that stops at the token limit, check whether the visible answer contains all three requested items. A valid HTTP response is not the same as a complete brief. Tighten the requested output or adjust the limit, then review the next result before connecting additional tools.
Frequently asked questions
Is the Claude API model ID the same on Bedrock?
The first-party API uses claude-fable-5-2. Anthropic lists a separate Bedrock model identifier. Follow your provider's route and deployment instructions.
How should I investigate an authentication error?
Check that the environment contains the intended key and that it belongs to the organization you meant to use. Keep credentials out of any screenshots or shared logs.
Work from the approved brief
Use Ciyo's Design agent once the source details and the visual task are ready for a real design pass.