Write the Comment, Then Wait
Copilot's inline suggestions are only as good as the surrounding signal. A descriptive function name plus a one-line comment of intent produces dramatically better completions than an empty body. Treat the comment as a mini-prompt: // parse an RFC3339 timestamp, return null on failure gets you a near-correct implementation in one keystroke.
Use the Right Chat Command for the Job
Copilot Chat ships purpose-built slash commands. Reach for them instead of describing the task in prose:
| Command | Use it for |
|---|---|
/explain | Understanding unfamiliar code you've selected |
/fix | Resolving an error or a flagged problem |
/tests | Generating unit tests for the selection |
/doc | Writing docstrings and comments |
Pull in Real Context with @workspace and #file
By default chat only sees your open file. Prefix a question with @workspace to let Copilot search the whole project ("@workspace where do we configure the database pool?"), or reference specific files with #file so it answers against the code that actually matters instead of guessing.
Set Custom Instructions Once
Drop a .github/copilot-instructions.md in your repo to encode standing rules — preferred libraries, naming conventions, "always use async/await, never .then()". Copilot applies them to every suggestion and chat response in that project, so you stop correcting the same things by hand.
Switch to Edit / Agent Mode for Multi-File Changes
Inline completion is for a single spot. When a change spans files — rename a concept, thread a new parameter through a call chain — use Copilot Edits (or agent mode) to propose a coordinated multi-file diff you review and apply together.
Copilot is confident even when wrong — it will happily invent an API that doesn't exist. Treat every suggestion as a draft from a fast junior dev: useful, but reviewed before it lands.
Accept Partially with Word-by-Word
You don't have to take or reject a whole suggestion. Accept it word-by-word (or line-by-line) when only the first part is right — it's faster than deleting the tail and re-prompting.
Frequently Asked Questions
Is Copilot Chat different from inline suggestions?
Yes. Inline suggestions complete code as you type; Chat is a conversational panel with slash commands, workspace search, and multi-file edits. Use both.
Will custom instructions slow Copilot down?
No meaningful impact. They're injected as context and mostly improve relevance, reducing the back-and-forth that actually costs you time.
Can Copilot see my whole repository?
Only when you ask it to via @workspace, or in agent mode. Plain inline completion is scoped to nearby code in the open file.