span.create
Log a span on an existing trace (or a batch).
How to use it
span.create is exposed by the Opik MCP MCP server. Add the server to your MCP client (Claude Desktop, Cursor, Windsurf and others), and the span.create tool becomes available to the model automatically. See the full listing for setup details and every tool this server provides.
Install Opik MCP
npx @modelcontextprotocol/inspector uvx opik-mcpOther tools in Opik MCP (15)
For investigative questions, cross-entity synthesis, or anything that needs
Attach a free-text comment to a trace, span, or thread.
Attach trace + datasetitem rows to an experiment.
Create an experiment scoped to a test suite.
Browse a collection with optional name filter and pagination. Project-scoped
Save a new prompt version (creates the prompt by name if missing).
One tool for any "show me X" question. Takes an entitytype plus an id
Run an evaluation experiment end-to-end via Ollie. Takes a single
Inspect the exact JSON shape and required fields of any write operation before
Attach a numeric feedback score to a trace, span, or thread.
Upsert items into a test suite (always the envelope shape).
Create an evaluation test suite.
Log a single trace (or a batch). Parent for spans / scores / comments.
Finalize or amend an existing trace.
Universal write dispatcher. Pass operation + data and the dispatcher