fix: sanitize tool input_schema for Anthropic adapter

When configuring Anthropic as the provider, any tool whose input_schema
contains a top-level oneOf/anyOf/allOf causes the API to reject the
entire request with HTTP 400:

  Anthropic API error (HTTP 400 Bad Request invalid_request_error):
  tools.1.custom.input_schema: input_schema does not support oneOf,
  allOf, or anyOf at the top level

The OpenAI Responses adapter already handles this via
schema_sanitize::sanitize_for_responses, which strips root-level
composition keywords, merges alternative properties into the root
object, and surfaces dropped constraints as a description note so the
model still knows which parameters are expected.

Apply the same sanitization in the Anthropic adapter before sending
tool definitions, aligning both adapters for consistent schema
handling across providers.

Harvested from PR #4346 by @qinlinwang

Author: qinlinwang

crates/tui/src/client/anthropic.rs

@@ -29,6 +29,7 @@ use serde_json::{Value, json};
 use crate::llm_client::StreamEventBox;
 use crate::logging;
 use crate::models::{ContentBlock, MessageRequest, MessageResponse, StreamEvent, Usage};
+use crate::tools::schema_sanitize;
 
 use super::{DeepSeekClient, ERROR_BODY_MAX_BYTES, bounded_error_text};
 
@@ -80,10 +81,23 @@ impl DeepSeekClient {
                 tools
                     .iter()
                     .map(|tool| {
+                        // Sanitize the tool's input_schema the same way the
+                        // OpenAI Responses adapter does: strip top-level
+                        // oneOf/anyOf/allOf (which Anthropic rejects), merge
+                        // alternative properties into the root, and surface
+                        // the dropped constraint as a description note so the
+                        // model still knows which parameters are expected.
+                        let mut schema = tool.input_schema.clone();
+                        let constraint_note = schema_sanitize::sanitize_for_responses(&mut schema);
+                        let description = match constraint_note {
+                            Some(note) if tool.description.trim().is_empty() => note,
+                            Some(note) => format!("{}\n\n{}", tool.description.trim(), note),
+                            None => tool.description.clone(),
+                        };
                         let mut value = json!({
                             "name": tool.name,
-                            "description": tool.description,
-                            "input_schema": tool.input_schema,
+                            "description": description,
+                            "input_schema": schema,
                         });
                         if let Some(strict) = tool.strict {
                             value["strict"] = json!(strict);