Claude Error Collector

An MCP server for Claude Code that learns from your corrections. When you tell Claude "that was wrong" or "no, do it like this", it records the lesson as a rule in your CLAUDE.md - so the same mistake doesn't happen twice.

How It Works

1. You correct Claude during a coding session
2. Claude recognizes the correction and calls the record_error tool
3. The server derives a rule and writes it to the appropriate CLAUDE.md
4. Claude reads that rule in future sessions and avoids repeating the mistake

The server automatically detects whether you're in a project directory (writes to project CLAUDE.md) or your home directory (writes to ~/.claude/CLAUDE.md).

Tools

record_error

Records a correction and saves it as a learned rule.

Parameter	Type	Required	Description
error_description	string	yes	What was wrong
correction	string	yes	What is correct
rule	string	yes	Derived guideline, e.g. "ALWAYS use X instead of Y"
project_dir	string	no	Current working directory (for finding project CLAUDE.md)

list_errors

Lists all learned rules from the relevant CLAUDE.md.

Parameter	Type	Required	Description
project_dir	string	no	Current working directory

Output Format

Rules are stored in a ## Learned Rules section in your CLAUDE.md:

## Learned Rules

- ALWAYS use async/await for API calls, NOT .then() chains
- Google Apps Script uses Logger.log(), NOT console.log()
- Confluence API expects ADF format, NOT Wiki markup

Installation

git clone https://github.com/henningziech/claude-error-collector-mcp.git
cd claude-error-collector-mcp
./install.sh

The install script handles everything:

1. Installs dependencies and builds the project
2. Registers the MCP server with Claude Code (claude mcp add)

No manual CLAUDE.md editing needed — the server provides its own instructions to Claude via MCP server metadata.

Restart Claude Code after installation to activate.

Manual Installation

If you prefer to set things up manually:

npm install && npm run build
claude mcp add error-collector -- node /path/to/claude-error-collector/dist/index.js

CLAUDE.md Resolution

The server finds the right CLAUDE.md using this logic:

1. If project_dir is provided: walk up the directory tree looking for CLAUDE.md
2. If found and not in the home directory: use it (project-level rules)
3. Fallback: ~/.claude/CLAUDE.md (global rules)

Duplicate Detection

Duplicate detection works on two levels:

1. Server-side: Before writing a rule, the server checks existing rules using case-insensitive substring matching. If the new rule is already covered by an existing one (or vice versa), it skips the write.

2. Semantic (via instructions): The server instructs Claude to review existing learned rules for semantic equivalence before calling record_error — even if the wording differs. Claude will:

   • Skip silently if the rule clearly already exists
   • Record it if the rule is clearly new
   • Ask the user if a similar rule exists but it's not 100% clear whether it's a duplicate, offering options to add alongside, consolidate, or skip

License

MIT