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This Open Source Friday interview introduces Serena, an open source toolkit that gives a coding assistant access to code symbols through MCP. In this interview, its co-creator explains the project's origins and demonstrates finding methods, retrieving file outlines and tracing references without reading entire files. Symbol editing can replace a method body without supplying the old text.
The setup discussion covers starting the Python MCP server with uvx, adding it to Codex configuration and activating the project in the current directory. Serena's dashboard shows tool calls, the active project and logs. A prepared Codex comparison uses the same code-analysis prompt with and without Serena, with memories disabled. The speaker reports roughly half the tokens and time for that example; this is a demonstration result rather than a general benchmark.
A Claude Code demo covers renaming, inlining, safe deletion and moving code through the JetBrains backend. Claude initially misses the move tool and uses it after another prompt. The speaker also says older models struggled with Serena's advanced tools, while newer models use them more effectively.
The language-server backend can run remotely or on a server without an open JetBrains IDE. The demonstrated advanced refactoring tools require the JetBrains plugin. VS Code users can connect through MCP or keep JetBrains open in the background for those tools. A native VS Code plugin is discussed as planned work.
