inquisitor — Claude Code MCP server: purpose and setup
inquisitor guides an agent through evidence-based checks before it settles on a fix. Use it when a project failure needs more than a blind retry.
claude mcp add inquisitor -- uvx inquisitor-mcpWhat inquisitor does
The agent starts by defining the expected result and what must remain unchanged. It then tests the leading explanation with a low-cost check. A straightforward local cause can go straight to a fix; unclear or multi-part failures call for deeper investigation. Web search and code tracing are used when local evidence falls short.
The server keeps a record of rejected explanations and the evidence against them. Once two explanations from the same line of reasoning fail, the agent must reconsider its assumptions or widen the investigation instead of repeating the approach. That guardrail adds process, so a simple typo should remain a simple fix.
To run it with Claude Code, use claude mcp add inquisitor -- uvx inquisitor-mcp; the project also lists Python 3.12+. The MCP server provides investigation tools, while a separate skill supplies the reasoning method. Certain changes, including infrastructure and authorization work, can trigger a deeper review.
What it helps with
- test a likely cause before changing code
- trace execution when an error has no clear source
- keep failed explanations and their disconfirming evidence
- change investigative direction after repeated failures
Example prompts for the agent
- Investigate why this request fails at runtime; test the likeliest cause first.
- Find the cause of this production-only error and show what evidence would rule it out.
- Two fixes have failed. Revisit the assumptions and test a different explanation.
How to install inquisitor
Platform CLI
claude mcp add inquisitor -- uvx inquisitor-mcpuvx runs the command named after the package; if the README names another one, use uvx --from inquisitor-mcp <command>
Platform CLI
codex mcp add inquisitor -- uvx inquisitor-mcpuvx runs the command named after the package; if the README names another one, use uvx --from inquisitor-mcp <command>
Config file
{
"mcpServers": {
"inquisitor": {
"command": "uvx",
"args": [
"inquisitor-mcp"
]
}
}
}uvx runs the command named after the package; if the README names another one, use uvx --from inquisitor-mcp <command>
Config file
{
"servers": {
"inquisitor": {
"type": "stdio",
"command": "uvx",
"args": [
"inquisitor-mcp"
]
}
}
}uvx runs the command named after the package; if the README names another one, use uvx --from inquisitor-mcp <command>
Platform CLI
gemini mcp add inquisitor uvx inquisitor-mcpuvx runs the command named after the package; if the README names another one, use uvx --from inquisitor-mcp <command>
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about inquisitor
How do I install inquisitor in Claude Code?
Run claude mcp add inquisitor -- uvx inquisitor-mcp. Python 3.12+ is also listed for running the server.
What does inquisitor do?
It helps an agent test possible causes, choose investigation depth based on probe results, and retain explanations that evidence has ruled out.
How does inquisitor prevent repeated failed attempts?
It records rejected explanations and why they failed. After two failures along the same line of reasoning, the agent must reconsider an assumption or broaden the investigation.
