docs: add executive summary for tool loading research

Co-authored-by: Tiberriver256 <6989492+Tiberriver256@users.noreply.github.com>

Author: Copilot

docs/research/SUMMARY.md

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+# Research Summary: Tool Loading Strategies
+
+## Problem Statement
+Our MCP server loads 43 tools at once, which can overwhelm LLMs and make tool selection less efficient.
+
+## Research Conducted
+Analyzed two Microsoft MCP server implementations:
+1. **microsoft/azure-devops-mcp** (TypeScript) - 79 tools total
+2. **microsoft/mcp Azure.Mcp.Server** (C#) - 128 tools total
+
+## Key Findings
+
+### Strategy 1: Domain-based Filtering ⭐ RECOMMENDED
+Used by microsoft/azure-devops-mcp
+- **Concept:** Users select which feature domains to load
+- **Example:** `--domains core work-items repositories` loads only those domains
+- **Reduction:** Variable based on user selection (typically 50-70% reduction)
+- **Complexity:** Low (1-2 days implementation)
+- **Default:** All domains (backward compatible)
+
+### Strategy 2: Multi-tier Mode System
+Used by Azure.Mcp.Server
+- **Concept:** Three abstraction levels
+  - Single mode: 1 unified tool
+  - Namespace mode: 25 service-level tools (default)
+  - All mode: 128 individual tools
+- **Reduction:** 81% in default mode (128 → 25)
+- **Complexity:** High (1-2 weeks implementation)
+- **Additional:** Supports consolidated intent-based grouping
+
+## Recommendation
+
+**Implement Domain-based Filtering** as Phase 1
+
+### Why?
+- ✅ Quick to implement (1-2 days)
+- ✅ Proven successful
+- ✅ Perfect fit with our architecture
+- ✅ Backward compatible
+- ✅ Low risk
+- ✅ Can evolve later
+
+### Proposed Domains
+Map existing features to domains:
+- `core` → organizations, projects, users (4 tools)
+- `work-items` → work items feature (5 tools)
+- `repositories` → repositories feature (9 tools)
+- `pull-requests` → pull requests feature (7 tools)
+- `pipelines` → pipelines feature (8 tools)
+- `wikis` → wikis feature (6 tools)
+- `search` → search feature (3 tools)
+
+### User Experience
+```bash
+# Load only work item tools
+npm run start -- --domains work-items
+
+# Load core + repositories
+npm run start -- --domains core repositories
+
+# Load everything (default, backward compatible)
+npm run start
+```
+
+## Next Steps
+1. Create `src/shared/domains.ts` with Domain enum and manager
+2. Update `src/index.ts` to parse domain arguments
+3. Modify `src/server.ts` for conditional tool registration
+4. Update documentation with domain usage examples
+5. Test with various domain combinations
+
+## Impact
+- **Tool reduction:** 50-90% depending on user selection
+- **Better LLM performance:** Fewer tools = better selection accuracy
+- **User control:** Users choose what they need
+- **Migration path:** Can upgrade to more sophisticated approaches later
+
+## Full Details
+See [tool-loading-strategies.md](./tool-loading-strategies.md) for complete analysis, code examples, and implementation guidance.