Glean indexes source code across the organization's connected repositories. Local tools (Grep, Glob, Read) see only the current repo; this skill is for everything else.
When to reach for this
- Finding the system — "Where does our payments code live?"
- Finding the patterns — "How do other teams handle rate limiting?"
- Finding the people — combining code authorship with
employee_searchreveals real owners (not just titled ones) - Prior art before designing — see reference/plan-prep.md for the research-before-plan workflow
- Cross-repo exploration — understanding systems, mapping breadth, finding contributors across the organization
The tool you'll mostly use
This skill drives the code_search MCP tool. For full param shape, inline filter syntax, and pitfalls (quoting names, the app: filter not applying, recency caveats), read ../using-glean/reference/code-search.md. That is the canonical reference; this skill carries the workflow on top.
For this skill's own workflow patterns, see:
- reference/exploration.md — exploring an unfamiliar system across repos: what to search for, what to filter, what to present
- reference/plan-prep.md — gathering enterprise context before entering plan mode for architectural / strategic work
Vetting
Not every match is worth surfacing. Code in legacy/, deprecated/, archive/, abandoned repos, or files with extensive TODO/FIXME comments will mislead the user. Apply the criteria in ../using-glean/reference/vetting.md and prefer 3 high-quality matches over 10 unfiltered ones.
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- STALE: 12+ months — likely outdated patterns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 |
Output expectations
When presenting code findings:
- Cite each file with its full URL so the user can open it directly
- Note last-update date when a result depends on currency (active patterns vs. archaeological digs)
- Group by repo when results span many repos — it shows the user the shape of the answer
- Flag drift when implementations disagree across teams — don't pretend consensus exists if it doesn't
Related skills
codebase-context— structured architecture rundown for an unfamiliar systemsimilar-code— find similar implementationsfind-examples— usage examples for an internal API or librarycode-owners— maintainers and contributorsplan-prep— the workflow described in reference/plan-prep.md