[alexa-sift]

Background: Every list_* MCP tool builds its response through list_body. A caller can pass fields: ["name", "asset_id"] to keep only those keys on each row. If a requested name matches nothing on any row (a typo like nmae), list_body adds unmatched_fields: ["nmae"]. Without that key, a typo would quietly return rows with that field missing, and the agent could report the data as empty when the field name was wrong. unmatched_fields lets the agent catch the mistake and retry, or at least tell the user.

The problem: serde_json sorts keys alphabetically, so unmatched_fields comes after the items array. In 7 of the 14 list tools (channels, assets, annotations, and others), the items key also sorts before count and has_more. The agent output guard cuts large responses from the end, so these keys disappear on exactly the big responses where they matter most.

The fix: a new list_result helper writes the text block agents read with every metadata key first and the items array last. All 14 list tools return through it. count, has_more, unmatched_fields, artifact_url, and next_step now survive head truncation regardless of how the items key sorts or whether serde_json's preserve_order is ever enabled. structuredContent is unchanged, and the key keeps its existing name.

Verification

• New list_result tests in common/test.rs:
  • All 14 items keys write count, has_more, and unmatched_fields before the items.
  • With 500 rows, all three sit in the first 200 characters.
  • The text block parses to the same JSON as structuredContent.
  • next_step gets its own leading block.
• Handler-level assertions on the text block for list_channels, list_artifact_versions (artifact_url first), and list_calculated_channel_versions (next_step block first).
• With list_result reverted to alphabetical output, 6 of the new tests fail.
• cargo fmt --check --all, cargo check --all-features, and cargo clippy --all-features pass with no new warnings. cargo test -p sift_mcp passes 605 tests.