MAJOR from the 2026-04-22 review (crates/mcp/src/lib.rs:188-195):
the handler called serde_json::from_value(args).unwrap_or_default(),
so a request like { "limit": "twenty" } silently became the default
limit of 20. Every other tool handler in this file map_errs to
-32602 Invalid arguments; this one was the outlier.
Switches to the same map_err pattern. Empty params still
deserialise cleanly to Args::default (via #[serde(default)] on the
Option<i64> field), so callers that send no args are unaffected —
only genuinely malformed shapes now error.
Regression test: tools/call with list_transcripts and a
string-typed limit must return code -32602 with an "Invalid
arguments" message.
Jake
840012822f