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Agent skill

Investigate

by adamthewilliam in adamthewilliam/grepika

This skill should be used when the user asks to "investigate a bug", "trace an error", "debug this issue", "find where this error comes from", or mentions keywords related to error tracing and bug…

MITAuto-check passedDevelopment

Install Investigate

skills CLI
$ npx skills add adamthewilliam/grepika --skill investigate -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install adamthewilliam/grepika investigate --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/adamthewilliam/grepika.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/grepika/skills/investigate .claude/skills/investigate && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
investigate
GitHub stars
138
Token cost
~762 tokens
SKILL.md length
258 words
Files
2 (incl. references)
Skills in repo
9
Repo updated
First seen
Licence
MIT

At a glance

This skill should be used when the user asks to "investigate a bug", "trace an error", "debug this issue", "find where this error comes from", or mentions keywords related to error tracing and bug…

  • Works in 5 steps: Search for the error/keyword → Get context around matches → Find references to key functions → …
  • Asks to investigate a bug
  • SKILL.md covers Input, Pre-check, Investigation Workflow and Output Format, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Investigate is an agent skill from adamthewilliam/grepika. This skill should be used when the user asks to "investigate a bug", "trace an error", "debug this issue", "find where this error comes from", or mentions keywords related to error tracing and bug investigation.

Its SKILL.md is about 760 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/error-patterns.md`). Compatibility notes: Requires grepika MCP server.

It sits in Development. It works with Model Context Protocol. The licence is MIT.

When your agent uses it

  • Asks to investigate a bug
  • Debug this issue
  • Find where this error comes from
  • Mentions keywords related to error tracing and bug investigation

Example prompts

  • “investigate a bug”
  • “trace an error”
  • “debug this issue”
  • “/investigate”

Requirements

  • Compatibility (from SKILL.md): Requires grepika MCP server.
  • Pre-approved tools (allowed-tools): mcp__grepika__search, mcp__grepika__refs, mcp__grepika__outline, mcp__grepika__context, mcp__grepika__get, mcp__grepika__graph, mcp__grepika__structural_search, mcp__grepika__add_workspace

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Search for the error/keyword
  2. Get context around matches
  3. Find references to key functions
  4. Discover connected files
  5. Extract file structure

What it can do on your machine

Read from SKILL.md and the folder at commit f035a18. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • mcp__grepika__search
    • mcp__grepika__refs
    • mcp__grepika__outline
    • mcp__grepika__context
    • mcp__grepika__get
    • mcp__grepika__graph
    • mcp__grepika__structural_search
    • mcp__grepika__add_workspace

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

  • Compatibility

    Requires grepika MCP server.

    From compatibility in the SKILL.md frontmatter.

Context cost

Investigate loads about 762 tokens when it runs, and up to ~1.7k if it reads all its reference files. Until then it costs about 56 tokens; SKILL.md has 258 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~56
When it runs · the whole SKILL.md, loaded when a task matches
~762
With references · SKILL.md plus every file in references/, read only if the agent opens them
~1.7k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from adamthewilliam/grepika at commit f035a18, republished under its MIT licence (© adamthewilliam). 258 words, ~762 tokens.

Download SKILL.mdSave it as .claude/skills/investigate/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
investigate
description
This skill should be used when the user asks to "investigate a bug", "trace an error", "debug this issue", "find where this error comes from", or mentions keywords related to error tracing and bug investigation.
allowed-tools
mcp__grepika__search, mcp__grepika__refs, mcp__grepika__outline, mcp__grepika__context, mcp__grepika__get, mcp__grepika__graph, mcp__grepika__structural_search, mcp__grepika__add_workspace
compatibility
Requires grepika MCP server.
version
1.1.0
disable-model-invocation
true
context
fork
agent
Explore
model
haiku

Debug Investigation Skill

You are a debugging investigator. Trace errors and bugs through the codebase to find their origin and call chain.

Input

Query: $ARGUMENTS

If no query provided, ask the user what error or bug they want to investigate.

Pre-check

If any tool returns "No active workspace", call mcp__grepika__add_workspace with the project root first, then retry the tool.

Investigation Workflow

  1. Search for the error/keyword

    • Use mcp__grepika__search with mode: "grep" for exact error message strings (regex patterns)
    • Use mcp__grepika__search with mode: "fts" for natural language variations (e.g., related concepts, similar error descriptions)
    • Use mode: "combined" (default) when you're unsure which approach fits best

  2. Get context around matches

    • Use mcp__grepika__context to see surrounding code for each match
    • Identify which matches are the actual error origin vs error handling

  3. Find references to key functions

    • Use mcp__grepika__refs to trace function calls
    • Build the call chain from entry point to error location

  4. Discover connected files

    • Use mcp__grepika__refs to find connected modules
    • Look for related error handling, logging, or retry logic

  5. Extract file structure

    • Use mcp__grepika__outline on key files to understand their shape
    • Identify relevant functions, classes, and exports

Output Format

Provide a structured investigation report:

## Error Investigation: [query]

### Origin
- **File**: [path:line]
- **Function**: [name]
- **Context**: [what the code does]

### Call Chain
1. [entry point] →
2. [intermediate call] →
3. [error location]

### Related Error Handling
- [list any try/catch, error boundaries, or recovery logic found]

### Investigation Points
- [specific lines/functions to examine further]
- [questions that remain unanswered]

### Suggested Fixes
- [potential approaches based on findings]

Tips

  • Start broad, then narrow down
  • Look for multiple occurrences - the same error may be thrown in different places
  • Check for error handling that might swallow or transform the original error
  • Note any logging that could help reproduce the issue

Additional Resources

See references/error-patterns.md for:

  • Common error message signatures and their meanings
  • Call chain analysis techniques
  • Error handling patterns to watch for

© adamthewilliam, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in plugins/grepika/skills/investigate of adamthewilliam/grepika.

  • SKILL.md
  • references/error-patterns.md

Open the folder on GitHubat commit f035a18

Compare with similar skills

Investigate next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Investigate compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Investigate this skilladamthewilliam/grepika138—~762Automated safety check: PassMIT
Debugging Executionsn8n-io/n8n207k—~2.6kAutomated safety check: PassCustom licence
ast-grep Structural Searchcode-yeongyu/oh-my-openagent70k—~3.3kAutomated safety check: PassMIT
Analyze Logsactivepieces/activepieces25k1 repos~1.6kAutomated safety check: PassMIT
Rea Changelog Updatemorluto/rea80k—~1.9kAutomated safety check: PassMIT
ReleasePrefectHQ/fastmcp28k—~2.9kAutomated safety check: PassApache-2.0

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    n8n-io/n8n

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Works with

Categories

Questions about Investigate

What does Investigate do?

This skill should be used when the user asks to "investigate a bug", "trace an error", "debug this issue", "find where this error comes from", or mentions keywords related to error tracing and bug…. Investigate is an agent skill from adamthewilliam/grepika. This skill should be used when the user asks to "investigate a bug", "trace an error", "debug this issue", "find where this error comes from", or mentions keywords related to error tracing and bug investigation.

When should I use Investigate?

Investigate fits situations like: asks to investigate a bug; debug this issue; find where this error comes from; mentions keywords related to error tracing and bug investigation.

How do I install Investigate in Claude Code?

Run `npx skills add adamthewilliam/grepika --skill investigate -a claude-code`. Or copy the skill folder (plugins/grepika/skills/investigate in adamthewilliam/grepika) into .claude/skills/investigate in your project. Claude Code loads it when a task matches its description.

How do I install Investigate in Codex?

Run `npx skills add adamthewilliam/grepika --skill investigate -a codex`. Or copy the skill folder (plugins/grepika/skills/investigate in adamthewilliam/grepika) into .agents/skills/investigate in your project. Codex loads it when a task matches its description.

Can I use Investigate in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add adamthewilliam/grepika --skill investigate -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/investigate, .gemini/skills/investigate, .github/skills/investigate and .opencode/skills/investigate in your project.

What does Investigate need to run?

SKILL.md names no scripts, command-line tools or credentials: Investigate is instructions for the agent only. Its frontmatter pre-approves these tools: mcp__grepika__search, mcp__grepika__refs, mcp__grepika__outline, mcp__grepika__context, mcp__grepika__get, mcp__grepika__graph, mcp__grepika__structural_search, mcp__grepika__add_workspace. Compatibility (from SKILL.md): Requires grepika MCP server..

Does Investigate access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Investigate safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Investigate use?

Investigate is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Investigate use?

About 762 tokens (SKILL.md is roughly 3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 985 tokens, read only when the agent opens those files.

What are the alternatives to Investigate?

Skills that share tags, products or a category with Investigate: Debugging Executions (n8n-io/n8n, 207k stars), ast-grep Structural Search (code-yeongyu/oh-my-openagent, 70k stars), Analyze Logs (activepieces/activepieces, 25k stars) and Rea Changelog Update (morluto/rea, 80k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Investigate?

adamthewilliam (a GitHub user) maintains it in adamthewilliam/grepika, which has 138 GitHub stars. The repository holds 9 skills in this directory. The repository was last updated on August 12, 2026.

Source: adamthewilliam/grepika on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.