patchwork-os

refactorExtractFunction

Destructive

Extract selected lines of code into a new named function to improve code readability and reusability.

Instructions

Extract lines into a named function. Uses VS Code Extract Function when available.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "file": "<file>",
      "startLine": "<startLine>",
      "endLine": "<endLine>",
      "functionName": "<functionName>"
    },
    "name": "refactorExtractFunction"
  }
}

Input Schema

Name	Required	Description
`file`	Yes	File path (relative to workspace)
`endLine`	Yes	End line (1-indexed)
`startLine`	Yes	Start line (1-indexed)
`functionName`	Yes	Name for the extracted function

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0May 20, 2026

TDQS

B3.4/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description mentions using 'VS Code Extract Function when available', which hints at integration behavior. However, it does not elaborate on side effects like file modification, error conditions, or undo capability. The annotation 'destructiveHint: true' already flags mutability, so the description adds limited value beyond that.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description consists of two short, front-loaded sentences with no redundancy. Every word contributes to understanding the tool's purpose and key behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a destructive tool (destructiveHint: true) with four required parameters and no output schema, the description lacks crucial context such as expected behavior on failure, whether the file is saved automatically, or any validation conditions. The brevity leaves the agent underinformed.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema provides 100% description coverage for all four parameters (file, startLine, endLine, functionName). The description adds no additional parameter information or usage examples, so it meets the baseline for schema-rich tools.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'Extract' and the resource 'lines into a named function', making the tool's purpose unambiguous. It distinguishes itself from sibling refactoring tools like 'refactorAnalyze' and 'refactorPreview' by specifying the exact action.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit guidance on when to use this tool versus alternatives like 'refactorPreview' or manual editing. The description does not mention prerequisites, conditions, or when not to use it, leaving the agent without decision support.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server