Cross-Repository Code Exploration via Glean
When users need to understand code across internal repositories—beyond the local codebase—use Glean's code search to explore the entire organization's code.
Tool Naming
See the glean-tools-guide skill for Glean MCP tool naming conventions. Tools follow the pattern mcp__glean_[server-name]__[tool] where the server name is dynamic.
When This Applies
Use Glean code search when users ask about:
- How something is implemented (in other repos)
- Where the code for a system/service lives
- Who has been working on a codebase
- Similar implementations across the org
- Examples of how to use an internal API/library
- Code patterns used by other teams
BE SKEPTICAL
Not every code result is worth presenting.
Quality Test
- Is this good code to reference?
- ✅ GOOD: Clean, tested, actively maintained
- ⚠️ ACCEPTABLE: Works but has caveats
- ❌ POOR: Hacky, deprecated, abandoned
Recency Test
- Is this code maintained?
- ✅ ACTIVE: Commits in past 3 months
- ⚠️ SLOWING: 3-12 months since last commit
- ❌ STALE: 12+ months - likely outdated patterns
Relevance Test
- Does this actually answer the question?
- ✅ RELEVANT: Directly addresses what was asked
- ⚠️ RELATED: Similar but different context
- ❌ TANGENTIAL: Keyword match only
Filter Out:
- Code in
/deprecated/,/old/,/legacy/paths - Abandoned repositories
- Prototype/experimental code
- Code with extensive TODO/FIXME comments
Quality over quantity: 3 good examples beat 10 mediocre ones.
Key Differentiator
Local tools (grep, glob) search only the current repo. Glean searches across ALL repositories in the organization. This is powerful for:
- Finding examples: "How do other teams handle authentication?"
- Understanding systems: "What repos touch the billing service?"
- Finding owners: "Who's been active in the payments codebase?"
Tool Selection
| User Intent | Glean Tool |
|---|---|
| Find code by content, pattern, or file | code_search |
| Find related design docs or specs | search |
| Identify code owners/contributors | code_search + employee_search |
| Read full file content | read_document |
Query Patterns
Glean's code search understands natural language. Use filters for precision:
# Search by content
code_search "authentication middleware"
code_search "rate limiting implementation"
# Search by contributor
code_search "owner:\"John Smith\" billing service"
code_search "from:me updated:past_week"
# Search by time
code_search "after:2024-01-01 payments API"
# Search by file pattern
code_search "*.proto user service"Workflow: Exploring a System
- Find the code:
code_search "[system name]" - Vet results: Filter for quality and recency
- Find the docs:
search "[system name] design doc OR architecture" - Find the people:
code_search "owner:* [system] updated:past_month" - Read details:
read_documentwith URLs from vetted results
If No Good Code Found
Don't pad with weak results:
No high-quality code examples found for [topic].
**What was searched:**
- [Queries attempted]
**What was filtered:**
- [X] matches - [reasons: outdated/poor quality]
**Suggestions:**
- Check external libraries
- Ask in [relevant channel]
- This may need to be built from scratchRelationship to Commands
For structured workflows, suggest the relevant slash command:
/glean-code:codebase-context [system]- Get comprehensive context/glean-code:find-examples [API/pattern]- Find usage examples/glean-code:code-owners [component]- Identify maintainers/glean-code:similar-code [pattern]- Find similar implementations