lsp-format-code

Requires the agent-lsp MCP server.

lsp-format-code

Format a file or selection using the language server's formatter — the same formatting engine your IDE uses. Applies language-specific rules (gofmt, prettier, rustfmt, black) without requiring those tools to be on PATH separately.

When to use

• Before committing: ensure consistent style across edited files
• After generating code: clean up AI-generated indentation and spacing
• After a refactor that shifted indentation levels
• When a linter flags style violations fixable by the formatter

Use /lsp-safe-edit instead when you are making a logic change and want before/after diagnostic comparison alongside the edit.

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Workflow

Step 1 — Check formatting is supported (optional)

If unsure whether the language server supports formatting for this file, check capabilities first:

mcp__lsp__get_server_capabilities({ "file_path": "<file>" })

Look for documentFormattingProvider (full-file) and documentRangeFormattingProvider (range). If neither is present, the server does not support formatting — stop and report.

Skip this step if you know the language supports formatting (Go, TypeScript, Rust, Python all do via their standard servers).

Step 2 — Open the file

mcp__lsp__open_document({ "file_path": "/abs/path/to/file.go", "language_id": "go" })

Step 3 — Request formatting edits

Full file:

mcp__lsp__format_document({ "file_path": "/abs/path/to/file.go" })

Selection only:

mcp__lsp__format_range({
  "file_path": "/abs/path/to/file.go",
  "start_line": <N>,
  "end_line": <M>
})

Both return TextEdit[] — a list of replacements to apply. They do not write to disk. If the list is empty, the file is already correctly formatted.

Step 4 — Apply the edits

Pass the TextEdit[] from Step 3 to apply_edit:

mcp__lsp__apply_edit({ "workspace_edit": <TextEdit[] from Step 3> })

This writes the formatting changes to disk.

Step 5 — Verify (optional but recommended)