Agent Trace Check in VS Code

Questions it answers

Agent Trace Check reads a tool-call log from an AI agent run and says what went wrong: which tools failed and how often, where the agent retried the same call in a loop, which calls it repeated with the same arguments, and which calls were slow.

Paste the log as JSON lines or one JSON value. It reads OpenAI chat messages with tool_calls, Responses API function_call items, Anthropic tool_use and tool_result blocks, Claude Code session JSONL files, MCP tools/call requests and their answers, LangSmith tool runs, OpenTelemetry tool spans, and flat rows with a tool name, arguments, a status or error, and a duration or timestamps.

Calls are paired with their results by id, or in order when the log has no ids. A call is slow at 10 seconds or more, or at 5 times its tool's median. A retry loop is 3 or more back-to-back calls to one tool where each repeats the last arguments or follows a failure. Both thresholds can be changed in one call.

The answer has findings ranked worst first, a table per tool with failures, median and slowest time and the most common error, and the lists of failures, retry loops, repeated calls and slow calls.

There is no account and nothing is stored. The log is read for the call and is not kept or cached, and no tool in it is called again. The only lasting record is a daily count of calls per tool.

What it can do

• Reads OpenAI, Anthropic, Claude Code, MCP, LangSmith, OpenTelemetry and flat JSON tool-call logs
• Pairs each tool call with its result by id, or in order when there are no ids
• Counts failures per tool and names the most common error
• Finds retry loops: back-to-back calls that repeat or follow a failure
• Finds the same call made again with the same arguments
• Lists slow calls by a fixed limit and by each tool's median time

Tools

• analyze_trace, Analyze an agent tool-call log. Use this when the user pastes a log of an AI agent's tool calls and wants to know which calls failed, where the agent retried in a loop, which calls it repeated, or which were slow. Pass the log as trace: JSON lines or one JSON value from OpenAI messages, the Responses API, Anthropic messages, Claude Code session JSONL, MCP JSON-RPC, LangSmith, OpenTelemetry spans, or flat rows with tool, args, status or error and duration_ms. Returns findings worst first, per-tool stats, failures, retry loops, repeated calls and slow calls. Nothing is stored. It does not run the agent or any tool.

Add Agent Trace Check in VS Code

VS Code reads MCP servers from mcp.json and offers their tools to Copilot Chat in Agent mode. A workspace file at .vscode/mcp.json applies to that project. For every workspace, run MCP: Open User Configuration from the Command Palette and add the same entry there. These steps were checked against the VS Code MCP servers guide on 2026-10-09.

Create or edit the file so it contains this server. VS Code uses a top-level servers object, not mcpServers. Merge it with servers you already have.

{
  "servers": {
    "agent-trace": {
      "type": "http",
      "url": "https://agenttrace.openkrill.app/mcp"
    }
  }
}

No command, no headers and no input variables for a key: Agent Trace Check answers without a login. Save the file and select Start above the entry. VS Code asks once whether you trust the server: confirm it. Run MCP: List Servers to check that Agent Trace Check is running. You should see analyze_trace.

Open the Chat view, choose Agent mode and ask: Analyze this agent tool-call log and tell me why the run failed. The Configure Tools button in the chat input lists the tools of each server, and VS Code may ask you to confirm the first call. The server is public and read-only. It sees only the arguments of each call, so do not paste secrets into the question.

Command line users can add it to the user profile in one step with code --add-mcp and the same name, type and url as JSON. The portable .mcp.json at the project root also works in VS Code, with mcpServers as its top-level key. An organization can turn MCP off through Copilot policy: if the MCP commands are missing, ask the admin.

If it does not work

A call checked on 2026-10-11

Four made-up log rows: one fetch that timed out 3 times in a row, then a search that worked. The tool reads only this text and calls nothing. The request below was posted to https://agenttrace.openkrill.app/mcp as tools/call. HTTP 200. Source: the Agent Trace Check server, read 2026-10-11.

{
  "method": "tools/call",
  "params": {
    "name": "analyze_trace",
    "arguments": {
      "trace": "{\"tool\":\"web_fetch\",\"args\":{\"url\":\"https://example.com/a\"},\"status\":\"error\",\"error\":\"timeout after 30000 ms\",\"duration_ms\":30000}\n{\"tool\":\"web_fetch\",\"args\":{\"url\":\"https://example.com/a\"},\"status\":\"error\",\"error\":\"timeout after 30000 ms\",\"duration_ms\":30000}\n{\"tool\":\"web_fetch\",\"args\":{\"url\":\"https://example.com/a\"},\"status\":\"error\",\"error\":\"timeout after 30000 ms\",\"duration_ms\":30000}\n{\"tool\":\"search\",\"args\":{\"q\":\"example\"},\"status\":\"ok\",\"duration_ms\":800}"
    }
  }
}

• notice. Computed from the pasted log alone. Nothing was stored, and no tool in the log was called again. Calls are matched by id, or in order when the log has no ids.
• findings. 3 returned
• by tool. 2 returned
• failures. 3 returned
• retry loops. 1 returned
• repeated calls. 1 returned

Repeat the call yourself if you need a newer reading. Cached answers expire. A rate limit is not a result: wait and try again. Nothing in the call is a ranking, a filing, or advice.

Using it in production

Nothing to install and nothing to run: no package, no Python or Node.js version and no environment variable. Agent Trace Check runs on our servers, and your client only needs the URL https://agenttrace.openkrill.app/mcp.

Use it in other apps

• Agent Trace Check in ChatGPT
• Agent Trace Check in Claude
• Agent Trace Check in Cursor
• Agent Trace Check in Pi

Frequently asked questions

Words on this page

• MCP (Model Context Protocol) definition
• Streamable HTTP transport definition
• Tool primitive definition
• Rate limit policy definition

Source: plugin listing for agent-trace in this repository, and a live tools/call on 2026-10-11. As of 2026-10-11.