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The Index API is a read API for the TKX and related series. {BASE} is the host issued when you Request Access. Headline readings are public. Fuller dated archive needs scope read-index.

Paths

Path	What it returns
/v1/index/tkx	Current headline series. A rising TKX means AI capability is getting cheaper; a falling TKX means it is getting more expensive.
/v1/index/tkx/history	Dated history (anonymous last 30 days)
/v1/index	Live series list
/v1/models	Model list
/v1/models/{id}	One model
/v1/methodology	Methodology record
/v1/tasks	Task list
/v1/events	Index events
/health	Health
/openapi.json	OpenAPI document

Index fields

source, asOf, series.tkx, series.tkx-open, series.tkx-frontier (each series includes asOf), freshness, scoringVersion, constructionVersion, methodology, marketHigh, marketLow. When the data may be behind (the last update is older than the previous weekday's close), freshness.state is STALE and freshness.lagging is true. The index level stays the same. Cambent pages show a behind reading as "Data may be behind — last updated {Mon D, YYYY}"; where a page shows a current reading, it reads "Data current as of {Mon D, YYYY}".

Model fields

input_price, output_price, quality_by_task, quality_source, price_source, grounding_tier, asOf.

Auth

Authorization: Bearer or X-Api-Key. Scope read-index for fuller history. Anonymous history is the last 30 days.

MCP

MCP is live. Request Access for connect details. The nine live tools:

• get_current_index
• get_index_history
• list_models
• get_model
• list_series
• list_tasks
• get_methodology
• list_models_by_task
• get_model_task_position

Cite the TKX: Source: Cambent TKX (https://tkx.cambent.ai), as of the response asOf. Methodology: https://cambent.ai/methodology.

Cambent publishes the signal; you decide.

Quickstart API