One call answers a question or a failing test's output with the spans
of the tree most likely to hold the cause, as path:start-end and their
lines, so an agent stops chaining grep and read.
Python is chunked by ast, other text in overlapping 40-line windows.
BM25 over code tokens is fused by reciprocal rank with the spans a
traceback's path:line frames name; when the query names a test file
the index holds, the code under test ranks first. Every search stats
the tree and re-chunks only what moved.
A dense stage (Qwen3-Embedding form, vectors cached by text hash) is
on only when HANZO_SEARCH_MODEL names a model: on the 42 dev tasks it
lifts span MRR .385 to .508, but a CPU query embedding takes seconds.
`python -m hanzo_search.server --root DIR` serves the tool alone over
stdio with the standard library, outside hanzo_mcp, whose import is
seconds long.
The `hanzo` mode lists it, so the default surface carries it; another
mode, `tool disable search` or HANZO_MCP_ENABLED_TOOLS decide it as they
decide every other tool.
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