deepseekcode

Tools

deepseekcode ships with 14 built-in tools. The model uses them via OpenAI-style function calling.

Tool Class Auto-allowed Notes
read_file read yes Returns content with cat -n line numbers. Optional start_line/end_line range. 2 MiB cap per file.
write_file mutate inside cwd Atomic write (tempfile + rename). Snapshotted before write.
edit_file mutate inside cwd String-replace with unique-match enforcement; replace_all opts in to multi-replace. Fuzzy hint when exact match fails (≤3 line-level edits). Snapshotted.
apply_patch mutate inside cwd Multi-hunk patch in *** Begin Patch / *** End Patch envelope. Add, Update (4-pass fuzzy match), Delete, Move. Replaces multiple edit_file calls. Snapshotted.
question read yes Asks the user one or more questions with selectable options. Single or multi-select. Blocks until answered.
bash execute per-pattern Runs in user shell with 120s default timeout. Permission gate per bashPattern matcher. Destructive bash triggers the Duet validator.
glob read yes Doublestar pattern (**/*.go). Skips .git, node_modules, .venv, etc.
grep read yes Regex search. Shells out to rg when present; falls back to a stdlib walker.
ls read yes Lists immediate children with [d]/[f]/[l] type indicators.
todo_write bookkeeping yes Manages the session’s structured plan. One in_progress item at a time.
git_diff read yes Unified diff between refs or working tree.
git_show read yes File content at a ref, or a commit’s metadata + diff.
git_blame read yes Reformatted per-line: path:line SHA author date content.
git_log read yes Compact: SHA date author: subject. Default 20 commits.

Permission tiers

Read-only tools never prompt. Mutating tools auto-allow inside the working directory; outside-cwd, .git/, .env*, or other secret-like paths always prompt. Bash prompts per unique command pattern with choices:

Override at startup:

Snapshots & /undo

Before each step that includes a mutating tool, affected files are snapshotted under .deepseek/snapshots/<sessionID>/<stepIdx>/. /undo restores the last step’s snapshots; /undo N restores N steps.

Bash effects are not statically known, so bash does not auto-snapshot. Use git status + the Duet validator to catch destructive bash output before it happens.

Extending: MCP

MCP (Model Context Protocol) servers are supported via config:

[mcp_servers.example]
command = "node"
args = ["/path/to/server.js"]
env = { FOO = "bar" }

Configured servers are connected at startup. None are enabled by default — the binary ships with the surface above. See docs/mcp.md for full configuration, lifecycle, and troubleshooting details.

Fuzzy matching in edit_file

When edit_file cannot find an exact match for old_string, it attempts a fuzzy fallback using line-level Levenshtein distance:

  1. The file is split into lines. A sliding window of the same line count as old_string is moved across the file.
  2. Each window is compared to old_string using LevenshteinLines (standard DP, O(n×m) on line tokens).

  3. If the closest window is within 3 line edits (insert, delete, or substitute), edit_file returns an error hint:

    old_string not found in path. Closest match at line N (distance D): "preview..."
  4. If the closest match exceeds 3 edits, the plain “not found” error is returned instead.

The fuzzy hint never auto-applies the change. The model (or user) must retry with the correct old_string. This prevents silent mis-edits while still providing actionable feedback on near-matches.

apply_patch envelope format

apply_patch uses a multi-hunk envelope format (aligned with the opencode/Codex convention) that lets the model express several file operations in a single tool call:

*** Begin Patch
*** Add File: path/new.go
+line1
+line2
*** Update File: path/existing.go
*** Move to: path/renamed.go        (optional)
@@ optional context header
 context line
-removed line
+added line
*** End of File                      (optional EOF anchor)
*** Delete File: path/old.go
*** End Patch

When to use apply_patch vs edit_file:

Safety: All paths are validated via path_safety (rejects escapes outside cwd, symlink traversal). Writes are atomic (tempfile + rename). Pre-tool snapshots cover every affected path so /undo reverts all files touched by one patch atomically.

question tool

question lets the model ask the user one or more questions with pre-defined options. It blocks until the user answers.

{
  "questions": [
    {
      "question": "Which database should we use?",
      "header": "Database",
      "options": [
        { "label": "pg", "description": "PostgreSQL" },
        { "label": "mysql", "description": "MySQL" }
      ],
      "multiple": false
    }
  ]
}

Parameters:

Field Type Required Description
questions array yes List of questions to present
questions[].question string yes The question text
questions[].header string no Short label (≤30 chars) shown in the UI
questions[].options array yes Selectable options (can be empty for skip-only)
questions[].options[].label string yes Answer label returned to the model
questions[].options[].description string no Extended description shown alongside the label
questions[].multiple boolean no Allow multi-select (default: false)

Behavior by mode:

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