Request Normalizer

The normalizer is an internal layer ported from mcp-filesystem-go-ultra. It runs before every tool handler and fixes common parameter issues without adding any new tools.

Why it exists

LLM clients (Claude Desktop, etc.) sometimes send parameters with slightly wrong names, wrong types, or inconsistent JSON encoding. Instead of returning errors, the normalizer silently corrects these before the handler sees them.

Parameter Aliasing

50+ rules map common parameter name variants to the canonical name.

Canonical	Accepted aliases
path	filepath, file_path, filename, file
old_text	old_str, oldText, old_string, search
new_text	new_str, newText, new_string, replace
source	src, from, source_path
destination	dest, dst, to, target, destination_path
content	text, data, body
pattern	query, search, regex
type	action, operation, op
recursive	recurse
include_content	search_content, content_search
file_types	extensions, ext, filetypes
chunk_index	index, chunk_number
total_chunks	chunks, num_chunks, total
chunk_size	size, bytes
create_backup	backup
follow_symlinks	symlinks, follow_links
exclude_patterns	exclude, ignore

Type Coercion

String values are converted to the expected Go type:

From	To	Example
"true", "false"	bool	"true" → true
"yes", "no"	bool	"yes" → true
"1", "0" (for booleans)	bool	"1" → true
Numeric strings	float64	"3" → 3.0

JSON Accept-Both

Array parameters accept either native JSON arrays or JSON-encoded strings:

// Both work:
{ "paths": ["/a.txt", "/b.txt"] }
{ "paths": "[\"/a.txt\", \"/b.txt\"]" }

Literal Escape Recovery

Claude Desktop sometimes sends \n as two literal characters (\ + n) instead of a real newline. The normalizer detects and fixes this in old_text and new_text parameters.

Idempotent Edits

If edit_file is called where new_text is already present in the file and old_text is absent, the edit is skipped gracefully instead of returning an error. This prevents retry loops.

Non-blocking No-match

When edit_file can’t find old_text in the file, it returns 0 replacements with a message instead of failing. The caller is told to re-read the file for current content.

Flexible Batch Fields

batch_operations accepts multiple field names for the same concept:

Concept	Accepted fields
Source	from, source, src, path, file
Destination	to, destination, dest, dst, target
Operation	type, action

Type aliases: cp → copy, rm / remove → delete.