MCP Agent Trace Inspector

npm `mcp-agent-trace-inspector` package

Local-first, MCP-native observability for agent workflows. Every tool call, prompt transformation, latency, and token count is recorded in a local SQLite database — no cloud account, no API key, no traces leaving your machine. Built specifically for MCP rather than bolted onto a generic LLM proxy.

Tool reference | Configuration | Contributing | Troubleshooting | Design principles

Key features

• Tool call tracing: Captures inputs, outputs, latency, and token usage for every step in a workflow.
• Persistent storage: Traces survive session restarts; stored locally in SQLite with no external dependencies.
• HTML dashboard: Generates a self-contained single-file dashboard with an interactive step timeline.
• Token cost estimation: Calculates USD cost per trace using a configurable model pricing table — no API calls required.
• Trace comparison: Diff two traces side by side to measure the impact of prompt or tool changes.
• Low overhead: Adds less than 5ms per step; never becomes the bottleneck.

Why this over LangSmith / AgentOps?

If your traces contain sensitive tool outputs, proprietary prompts, or data that must stay on-device, this is the right tool. If you need cross-team trace sharing or a managed SaaS, use LangSmith.

Disclaimers

`mcp-agent-trace-inspector` stores tool call inputs and outputs locally in a SQLite database. Traces may contain sensitive information passed to or returned from your tools. Review trace contents before sharing dashboard exports. Traces are not automatically transmitted; optional alert webhooks are available.

Requirements

• Node.js v22.5.0 or newer.
• npm.

Getting started

Add the following config to your MCP client:

{
  "mcpServers": {
    "trace-inspector": {
      "command": "npx",
      "args": ["-y", "mcp-agent-trace-inspector@latest"]
    }
  }
}

To set a custom storage path:

{
  "mcpServers": {
    "trace-inspector": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-agent-trace-inspector@latest",
        "--db=~/traces/my-project.db"
      ]
    }
  }
}

MCP Client configuration

Amp · Claude Code · Cline · Cursor · VS Code · Windsurf · Zed

Your first prompt

Enter the following in your MCP client to verify everything is working:

Start a trace called "test-run", then list the files in the current directory, then end the trace and show me the summary.

Your client should return a summary showing step count, total tokens, and latency.

Tools

Trace lifecycle (3 tools)

• `trace_start` — begin a new trace; returns a `trace_id` for subsequent calls
• `trace_step` — record one tool call step (inputs, outputs, optional token count and latency)
• `trace_end` — mark a trace as completed

Inspection (4 tools)

• `list_traces` — list stored traces with names, statuses, and timestamps
• `get_trace_summary` — token totals, step count, latency, and cost estimate for a trace
• `compare_traces` — diff two traces side by side (step counts, tokens, latency)
• `extract_reasoning_chain` — extract only reasoning/thinking steps from a trace

Export (3 tools)

• `export_dashboard` — generate a self-contained single-file HTML dashboard with latency waterfall
• `export_otel` — export one or all traces in OpenTelemetry OTLP JSON span format
• `export_compliance_log` — export the compliance audit log as JSON or CSV, with optional date range filtering

Operations (3 tools)

• `configure_alerts` — configure alert rules on latency, error rate, or cost; fire to Slack or generic webhooks
• `set_retention_policy` — set how many days to keep traces (in-memory; must be called before `apply_retention`)
• `apply_retention` — archive traces older than the configured threshold; delete traces past 2x the threshold

Configuration

`--db` / `--db-path`

Path to the SQLite database file used to store traces.

Type: `string`

Default: `~/.mcp/traces.db`

`--retention-days`

Automatically delete traces older than N days. Set to `0` to disable.

Type: `number`

Default: `0`

`--pricing-table`

Path to a JSON file containing custom model pricing ($/1K tokens). Overrides the built-in table.

Type: `string`

`--no-token-count`

Disable tiktoken-based token counting. Traces will omit token usage metrics.

Type: `boolean`

Default: `false`

Pass flags via the `args` property in your JSON config:

{
  "mcpServers": {
    "trace-inspector": {
      "command": "npx",
      "args": ["-y", "mcp-agent-trace-inspector@latest", "--retention-days=30"]
    }
  }
}

Design principles

• Append-only traces: Steps are immutable once recorded. Trust requires integrity.
• Local-first: All core functionality works without a network connection.
• Portable dashboards: HTML exports are always single-file; no server required to view them.

Verification

Before publishing a new version, verify the server with MCP Inspector to confirm all tools are exposed correctly and the protocol handshake succeeds.

Interactive UI (opens browser):

npm run build && npm run inspect

CLI mode (scripted / CI-friendly):

# List all tools
npx @modelcontextprotocol/inspector --cli node dist/index.js --method tools/list

# List resources and prompts
npx @modelcontextprotocol/inspector --cli node dist/index.js --method resources/list
npx @modelcontextprotocol/inspector --cli node dist/index.js --method prompts/list

# Call a tool (example — replace with a relevant read-only tool for this plugin)
npx @modelcontextprotocol/inspector --cli node dist/index.js \
  --method tools/call --tool-name list_traces

# Call a tool with arguments
npx @modelcontextprotocol/inspector --cli node dist/index.js \
  --method tools/call --tool-name list_traces --tool-arg key=value

Run before publishing to catch regressions in tool registration and runtime startup.

Contributing

See CONTRIBUTING.md for full contribution guidelines.

npm install && npm test

MCP Registry & Marketplace

This plugin is available on:

• MCP Registry
• MCP Market

Search for `mcp-agent-trace-inspector`.