Messages API

POST https://asklethe.ai/v1/messages accepts the same request shape as Anthropic’s Messages API. This is the endpoint to use if you’re porting code written against the Anthropic SDK, or pointing Claude Code at LETHE (see the Quickstart Claude Code snippet).

curl https://asklethe.ai/v1/messages \
  -H "x-api-key: $LETHE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "lethe",
    "max_tokens": 1024,
    "messages": [{ "role": "user", "content": "Say hi in five words." }]
  }'

Model aliasing

Any claude-* or anthropic.* model id (e.g. Claude Code’s default opus/sonnet/haiku picker ids) is automatically mapped to lethe, you don’t need to change model names in existing Anthropic-SDK code.

`thinking` / `output_config` normalization

LETHE normalizes a couple of Anthropic-shape edge cases before forwarding upstream:

"thinking": false is rewritten to {"type": "disabled"}.
output_config.effort: "none" is dropped in favor of thinking: {"type": "disabled"}.

You don’t need to do anything for this. It happens automatically if your client sends the older shape.

Count tokens

POST https://asklethe.ai/v1/messages/count_tokens mirrors Anthropic’s token-counting endpoint, same request body shape as /v1/messages minus generation params. Both endpoints share auth, quota, and error format with the rest of the API. See Authentication, Rate Limits, and Errors.

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Messages API

Model aliasing

`thinking` / `output_config` normalization

Count tokens

​Model aliasing

​thinking / output_config normalization

​Count tokens

Model aliasing

`thinking` / `output_config` normalization

Count tokens