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• ❌ STALE: 12+ months - likely outdated patterns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_document with 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:

• matches - [reasons: outdated/poor quality]

Suggestions:

• Check external libraries
• Ask in [relevant channel]
• This may need to be built from scratch

Relationship 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