# How do I tag a call site so graders can bind to it?

Set `tessary.call_site.id` as a plain attribute on the span you want tracked; that's the whole mechanism, no SDK required. Any OpenTelemetry exporter you already have can carry it, since it's just another span attribute alongside the ones you already send. If you'd rather not touch your agent's calling code at all, an OpenTelemetry Collector attributes or transform rule can add the tag in transit, fleet-wide, which is inert to every other consumer reading the same stream. Pick an id per function you actually want a separate history for, a specific prompt, a specific tool loop, not per request or per user; the id is what findings, baselines, and regressions key off, so it should name the code, not the call. A tagged span with no matching call site on record just creates one automatically, so a newly tagged span is gradable right away instead of waiting on setup elsewhere.

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Source: https://tessary.ai/answers/tessary-call-sites/how-do-i-tag-a-call-site
More on Tessary call sites: https://tessary.ai/answers/tessary-call-sites
From Tessary, agent reliability for AI agents in production: https://tessary.ai