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IAB Tech Lab’s buyer agent includes a Mixpeek client. With it configured, the agent gets three MCP tools:

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Configure the agent

Set these in the buyer agent’s .env:
classify_content and check_brand_safety need a retriever over IAB categories. If you do not pass retriever_id, the agent uses a retriever in the namespace whose name contains both iab and text.

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Build the IAB namespace

The classifier is semantic search over the taxonomy: each IAB Content Taxonomy 3.1 category becomes a document whose text is its name and path, embedded with the text extractor. Each document must keep iab_category_name, iab_tier and iab_path, which are the fields the buyer agent reads from the results.
  1. Create a namespace with the text_extractor.
  2. Set a spend budget on it. A new namespace starts at $0.00 per day, and the embedding batch fails on that budget.
  3. Create a bucket and upload one object per category, with the text in a category_text blob and iab_category_id, iab_category_name, iab_tier and iab_path as fields. Leave unique_key off the bucket if you load it with the batch endpoint, which refuses buckets that declare one.
  4. Create a collection with text_extractor, input_mappings: {"text": "category_text"} and field_passthrough for the four iab_ fields, then trigger it.
  5. Create a retriever named iab_text_search with one feature_search stage on mixpeek://text_extractor@v1/multilingual_e5_large_instruct_v1, querying {{INPUT.query}}.
A complete, tested script is in the guide Using Mixpeek in the IAB Tech Lab buyer agent.

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Behavior to know

  • The number of results comes from the retriever’s final_top_k. The tools’ limit argument does not reduce it.
  • check_brand_safety matches categories by exact name. At buyer-agent commit 47ac319, seven of its fourteen names are not Content Taxonomy 3.1 names, so content in those areas is classified but not flagged. Compare the returned categories against your own list of 3.1 names if you rely on the flag.
  • risk_level is high only when a flagged score is 0.85 or above.