Dumping a 500-page PDF into Claude 4.7 is a great way to burn API credits and induce hallucinations. Here is how to optimize context windows using semantic pre-filtering and XML framing.
Claude 4.7 has a massive context window. But just because you can paste a 500-page legal PDF into the prompt doesn't mean you should . If you do, you suffer from the "Lost in the Middle" phenomenon, where the model forgets clauses buried in page 250.
Context Pre-Filtering
If you are building Legal AI systems, you must filter the noise before it hits the LLM. If the user is asking about indemnification, do not send the entire Master Services Agreement. Run a local TF-IDF or fast vector search to extract only the 5 pages that contain the words "indemnify", "liability", and "hold harmless".
XML Framing Architecture
Once you have the filtered context, you must bound it using strict XML tags. Anthropic's models are highly tuned to recognize data encapsulated in XML.
<system_instructions>
You are a senior contract analyst. Answer the user's question using ONLY the provided document excerpts.
</system_instructions>
<document_excerpts>
<excerpt id="1" source="MSA_Page_42">
[FILTERED TEXT HERE]
</excerpt>
</document_excerpts>This drastically reduces token cost, drops latency from 40 seconds to 4 seconds, and eliminates hallucinations. That is how you deploy human capability multiplication at scale.
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