# Task ID: 84

**Title:** Implement Section Drill-Down for Tool Results

**Status:** done

**Dependencies:** 82 ✓

**Priority:** medium

**Description:** Extend tool result handling to support _section parameter for drilling into specific sections of large tool responses.

**Details:**

Modify tool call handling in `src/mcplocal/src/router.ts`:

```typescript
// When processing tool calls
if (args._section) {
  const sectionId = args._section;
  delete args._section; // Don't pass to upstream
  
  // Check cache for previous full result
  const cacheKey = `tool:${serverName}/${toolName}:${JSON.stringify(args)}`;
  const cachedResult = this.toolResultCache.get(cacheKey);
  
  if (cachedResult?.sections) {
    const section = findSection(cachedResult.sections, sectionId);
    if (section) {
      return { content: [{ type: 'text', text: section.content }] };
    }
  }
  // If no cache, make the full call and process, then serve section
}

// After receiving tool result, process through pipeline
const processed = await this.processContent(result, 'toolResult', `${serverName}/${toolName}`, sessionId);
if (processed.sections) {
  this.toolResultCache.set(cacheKey, processed);
}
```

Add a toolResultCache Map with appropriate TTL.

**Test Strategy:**

Integration tests: large tool result gets processed into sections, _section parameter returns specific section, _section removed before upstream call, cache hit serves from cache, cache miss processes and caches.