NLWeb Tools Framework

Before writing code

Fetch live docs:

1. Fetch https://github.com/nlweb-ai/NLWeb/blob/main/docs/tools.md for the canonical tools framework reference.
2. Fetch https://github.com/nlweb-ai/NLWeb/blob/main/config/site_types.xml for the per-type tool inheritance tree.
3. Read AskAgent/python/core/router.py::ToolSelector for how routing actually picks a tool.
4. Read existing handlers in AskAgent/python/methods/: generate_answer.py, item_details.py, compare_items.py, ensemble_tool.py, recipe_substitution.py, accompaniment.py.
5. Fetch https://github.com/nlweb-ai/NLWeb/blob/main/docs/nlweb-prompts.md for the <returnStruc> JSON contract that handlers must satisfy.

Conceptual Architecture

What a "Tool" Is in NLWeb

Confusingly, "tool" means two different things in NLWeb depending on context:

1. Internal tool / handler — a Python module in methods/ that the ToolSelector routes a query to (e.g., compare_items.py). This is the meaning used in this skill.
2. MCP tool — the JSON-RPC tool exposed at /mcp (ask, list_sites, who). See the nlweb-mcp-server skill for that meaning.