axiom

Axiom is a source-available tool that functions as both a CLI and an MCP server, indexing a codebase into a symbol graph to answer agent queries. It is described as "One binary that is both a CLI and an MCP server. It indexes a codebase into a symbol graph and answers an agent's questions against it: what does this symbol look like, which tests can reach it, does this snippet actually run, and what was checked before this change was recorded." It operates alongside Git and CI, aiming to reduce iteration time for agents by providing fast, local answers instead of waiting for remote CI. "Axiom sits beside Git and CI rather than replacing them. Git stores your history and CI gates your merges. Axiom removes the round trip an agent pays on every iteration: instead of pushing and waiting minutes to learn that a change broke something, the agent asks which tests can reach the symbol it touched, runs a snippet in that symbol's own language, and gets an answer in milliseconds." The tool offers three main strengths: blast-radius test selection, coordination of multiple agents via a shared operation log, and near-instant code search using an in-memory trigram index. "The blast radius walks the reverse dependency graph from a changed symbol to the tests that can observe it, so an agent runs those tests and skips the rest." "Mutations are recorded to a shared, commutative operation log backed by a Tree-CRDT, so agents in separate processes converge on the same tree whatever order their work lands in, with no locks and no merge conflicts." "The server keeps an in-memory trigram index over the scanned tree." Axiom provides eight MCP tools for symbol queries, blast radius, snippet evaluation, mutation application, and more. It supports multiple languages and can use SCIP indexes for precise symbol graphs. "Axiom implements the Model Context Protocol (MCP). Any MCP-compatible agent (Claude Code, Claude Desktop, Cursor, Windsurf) can connect to it."