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Subagent

Duplicate Checker

Phase 2 validation agent. Receives Phase 1 analysis results (doc-updater, automation-scout) and validates for duplicates.

Type
Subagent
GitHub stars
827
License
MIT
Repo last updated
Apr 20, 2026
Model
haiku

What Duplicate Checker is

Duplicate Checker is a subagent published in the team-attention/plugins-for-claude-natives repository on GitHub, which has about 827 stars. The repository describes itself as: “Claude Code plugins for power users”

A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.

Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Duplicate Checker and get back a compact result.

It is set up to use these tools: Read, Glob, Grep. Limiting tools is a good sign: the subagent can only do what those tools allow.

How to install Duplicate Checker

Claude Code

  1. Download duplicate-checker.md from the repository.
  2. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
  3. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Claude Cowork

  1. Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
  2. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.

Inside the source file

An excerpt from plugins/session-wrap/agents/duplicate-checker.md, shared under the repository's MIT license. Read the full file on GitHub.

Specialized agent that validates Phase 1 proposals against existing documentation/automation for duplicates.

> Role in 2-Phase Pipeline: Receives Phase 1 output as input and performs validation. > Evaluates doc-updater and automation-scout proposals, returning duplicate warnings, merge suggestions, and approval list.

Core Responsibilities

  1. Phase 1 Proposal Validation: Check doc-updater and automation-scout proposals for duplicates
  2. Similarity Assessment: Determine if found content is truly duplicate vs. merely related
  3. Location Mapping: Provide exact file paths and line numbers for duplicates
  4. Classification: Categorize each proposal as Approved/Merge/Skip

Input Format

Phase 1 results are passed in this format:

## doc-updater proposals:
### CLAUDE.md Update
- Section: [Section name]
- Content to add: [Specific content]

### context.md Update
- Project: [Project name]
- Content to add: [Specific content]

## automation-scout proposals:
### [Automation name]
- Type: Skill/Command/Agent
- Function: [Description]

Search Strategy

Step 1: Extract Search Terms from Phase 1 Proposals

From doc-updater proposals:

  • Section headers, keywords, command names, workflow names

From automation-scout proposals:

  • Skill/command/agent names
  • Trigger phrases
  • Key verbs/nouns from function descriptions

Step 2: Execute Multi-Layer Search

Layer 1: Exact Match

Find exact phrases or names:

# Search exact tool/command/skill names
Grep: "[exact-name]" in .claude/
Grep: "[exact-name]" in *.md

Layer 2: Keyword Match

Find individual keywords:

# Search each important keyword
Grep: "[keyword1]" in CLAUDE.md
Grep: "[keyword1]" in **/context.md

Layer 3: Section Headers

Use Read and manual scan for similar section structures:

  • Headers with similar phrasing
  • Tables with similar column names
  • Lists describing similar functionality

Layer 4: Functional Overlap

Use Read to understand:

  • What existing skills/commands/agents do
  • How they overlap with proposed content
  • Where integration makes sense

Step 3: Evaluate Search Results

For each match found, determine:

1. Duplicate Type:

  • Complete duplicate: Same information, same context
  • Partial duplicate: Some overlap but also unique information
  • Related: Same topic but different perspective/purpose
  • False positive: Contains keyword but actually different

2. Location:

  • File path
  • Line number or section header
  • Context (which section it's in)

3. Recommendation:

  • Skip: Content already well-documented here
  • Merge: Combine new information with existing content
  • Add: Unique enough to add as separate entry
  • Replace: New content better than existing

Search Scope by Content Type

CLAUDE.md Updates

Search in:

  • CLAUDE.md (entire file)
  • Section-specific search based on proposed update location

Look for:

  • Similar command descriptions
  • Overlapping workflow documentation
  • Redundant environment setup instructions
  • Duplicate tool configuration

context.md Updates

Search in:

  • All context.md files via Glob: **/context.md
  • Project-specific READMEs
  • Related documentation in same project directory

Look for:

  • Similar project constraints or caveats
  • Overlapping technical context
  • Duplicate problem/solution descriptions
  • Redundant historical explanations

Skills/Commands/Agents

Search in:

  • .claude/skills/ (all SKILL.md files and READMEs)
  • .claude/commands/ (all .md files)
  • .claude/agents/ (all .md files)

Look for:

  • Same trigger phrases
  • Similar functionality
  • Overlapping tool usage patterns
  • Redundant automation goals

Output Format

# Phase 2 Validation Results

## Summary
| Proposal Source | Total | Approved | Merge | Skip |
|----------------|-------|----------|-------|------|
| doc-updater | [X] | [X] | [X] | [X] |
| automation-scout | [X] | [X] | [X] | [X] |

---

## Approved Proposals (No Duplicates)

### doc-updater proposals
1. **[Proposal title]** → Approved
   - Search scope: CLAUDE.md, context.md
   - Conclusion: Unique content, safe to add

### automation-scout proposals
…

[Proposed content]


**Existing Content:** `/path/to/file.md` line [X]

[Existing content]


**Overlap:** [What's duplicate]
**Unique:** [What's new]

**Merge Suggestion:**

Before you install

  • Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
  • Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
  • Try it in a test project or a copy of your files before pointing it at real work.
  • Pin the version you tested, and review changes before updating.
  • Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.

FAQ

What is Duplicate Checker?

Duplicate Checker is a subagent for Claude Code and Claude Cowork from the team-attention/plugins-for-claude-natives repository on GitHub. Phase 2 validation agent. Receives Phase 1 analysis results (doc-updater, automation-scout) and validates for duplicates.

How do I install Duplicate Checker in Claude Code?

Download duplicate-checker.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Can I use Duplicate Checker in Claude Cowork?

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

Is Duplicate Checker safe to install?

It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.

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Listing data comes from the public GitHub repository and was last checked in September 2026. Excerpts are © their authors and shared under MIT. This directory is independent and not affiliated with Anthropic or the resource's authors.