Create an Anthropic Message

Native Anthropic Messages for the listed Claude models. Authenticate with your reAPI key; no group lookup or group parameter is needed. Returns the result directly or via SSE, with no automatic retries. Model-specific and beta capability restrictions are documented on each model page.

post/messages

Request

  • Base URL: https://reapi.ai/api/v1
  • URL: https://reapi.ai/api/v1/messages
  • Auth: one of:
    • API key in header x-api-key
    • HTTP bearer

Headers

anthropic-versionstring

Anthropic protocol version; reAPI supplies this default when omitted for native Claude.

anthropic-betastring

Optional beta feature flags. A flag does not guarantee that the selected model route supports the feature.

Request body

model'claude-haiku-5-5' | 'claude-sonnet-5-5' | 'claude-opus-5-5' | 'claude-fable-5' | 'claude-fable-5-1' required
max_tokensinteger required

Required output ceiling, including thinking tokens. Zero is forwarded for cache warmup; availability and behavior are determined upstream.

streamboolean
output_configobject

Native effort and structured output. output_config.format.schema is preserved unchanged. Supported effort values depend on the model; see its API documentation.

thinkingobject

Official thinking options. Thinking modes depend on the model. Haiku 5.5 supports disabled thinking; Sonnet 5.5 supports between_tools at low, medium or high effort. Beta options pass through.

toolsobject[]
tool_choiceobject
stop_sequencesstring[]
cache_controlobject nullable
temperaturenumber
top_pnumber
top_kinteger
metadataobject
diagnosticsobject nullable

Forwarded unchanged. Availability and parameter behavior are determined upstream; acceptance alone does not verify an effect.

service_tierstring

Forwarded unchanged. Availability and parameter behavior are determined upstream; acceptance alone does not verify an effect.

inference_geostring nullable

Forwarded unchanged. Availability and parameter behavior are determined upstream; acceptance alone does not verify an effect.

context_managementobject nullable
mcp_serversobject[]
speedstring nullable

Forwarded unchanged. Availability and parameter behavior are determined upstream; acceptance alone does not verify an effect.

compactionobject nullable
output_formatobject nullable

Response

Anthropic Message or native SSE events

idstring
type'message'
role'assistant'
modelstring
contentobject[]
stop_reasonstring nullable
usageobject

Changes