Structured execution trace and span logging for AI agents
Trace MCP server exists for a simple reason — assistants are far more useful when they can act on Trace directly instead of describing what you should do. Structured execution trace and span logging for AI agents.
MCP server for writing structured traces, spans, and decisions. The only write-path observability MCP — all 9 existing observability MCPs are read-only.
Once Trace is connected, these are the calls the assistant has available:
trace_tool_call — after each tool invocationtrace_decision — at each decision pointtrace_start — The trace_start tool exposed by this servertrace_span — Create a span within a trace. Spans can be nested via parent_span_idtrace_end — Complete a trace. Auto-calculates total duration, event counts, and span countsget_trace — Retrieve a complete trace tree with all spans, events, tool calls, and decisionssearch_traces — Returns: Matching traces sorted by recency with summary statsThe server ships on npm as trace-forge-mcp, so your MCP client can launch it on demand — there is no separate build step. Add the server block to your client's configuration, restart it, and the tools register themselves.
This sits in the developer tooling group, where several servers overlap in what they claim to do but differ sharply once you actually set them up. Trace's toolset — trace_tool_call, trace_decision, trace_start and 4 more — is a fair guide to whether it matches your workflow. It is maintained by mdfifty50-boop; worth a glance at recent repository activity before you build anything load-bearing on it.
This entry was verified against Trace's own documentation before publication; SyncDev keeps the directory reviewed rather than auto-generated.
| Tool | What it does |
|---|---|
| trace_tool_call | after each tool invocation |
| trace_decision | at each decision point |
| trace_start | The trace_start tool exposed by this server. |
| trace_span | Create a span within a trace. Spans can be nested via parent_span_id. |
| trace_end | Complete a trace. Auto-calculates total duration, event counts, and span counts. |
| get_trace | Retrieve a complete trace tree with all spans, events, tool calls, and decisions. |
| search_traces | Returns: Matching traces sorted by recency with summary stats. |
{
"mcpServers": {
"trace-forge": {
"command": "npx",
"args": ["-y", "trace-forge-mcp"]
}
}
}Add to claude_desktop_config.json, then restart Claude Desktop.
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