MCP AST Explorer vs Constellation

LibCST-based Python source indexing

Definition and signature lookup

Same-module reference search

Direct caller detection

Simple direct subclass detection

Structured missing-symbol and unsupported-language errors

code_intel

DECISION RULE: Structure questions → this tool. Text search → Grep. Before using Grep, ask: Is this a STRUCTURE question (definitions, callers, impact) or a TEXT question (strings, config)? QUICK START: `return await api.searchSymbols({query: "AuthService"})` — simple queries are one-liners. Run `api.listMethods()` for full API reference with signatures and descriptions. Run `api.help("methodName")` for inline TypeScript type definitions — no resource reads needed. Compose: `const [impact, deps] = await Promise.all([api.impactAnalysis({symbolId}), api.getDependents({filePath})]);` WHY THIS TOOL: Graph-backed intelligence finds indirect relationships, transitive dependencies, and breaking change risks that text search cannot detect. "What uses X?" disambiguation: getDependents (file imports) vs getCallGraph (call chain) vs traceSymbolUsage (all usages). USE IMMEDIATELY WHEN: • BEFORE using Edit on a function/class → run impactAnalysis({symbolId}) first • BEFORE exploring an unfamiliar codebase → run getArchitectureOverview() • BEFORE refactoring → trace getDependencies + getDependents for blast radius • Running 3+ Grep calls for structure? STOP → use code_intel instead TOP 5 QUESTIONS (query is case-insensitive substring match): • "Where is X defined?" / "Find function Y" → searchSymbols({query}) • "What calls X?" / "What imports this?" → getDependents({filePath}) or getCallGraph({symbolId}) • "What does X depend on?" → getDependencies({filePath}) • "Safe to modify X?" / "Blast radius?" → impactAnalysis({symbolId}) • "Find dead code" / "Unused exports?" → findOrphanedCode() • "Complex functions?" / "Refactoring targets?" → searchSymbols results include complexity.cyclomaticComplexity + complexityRisk per function NOT FOR: literal string search, log messages, config values, or reading source code. Use Grep/Glob/Read for those. Supports TypeScript, JavaScript, Python, and more — run api.getCapabilities() to check your project. File-path-scoped methods (getDependencies, getDependents, getCallGraph, traceSymbolUsage, impactAnalysis) reject calls whose `filePath` extension is not in the project's configured languages with `UNSUPPORTED_LANGUAGE` — check api.getCapabilities() first. WRONG TOOL SIGNAL: If you've run 3+ Grep calls for structure (callers, dependencies, impact), STOP and use code_intel instead. Typical workflow: code_intel to find (results include source snippets) → Edit to modify Sandbox limits: 50 api.* calls per execution, 128 MB memory, 100 KB max code size, `limit` max 100 on any method with a `limit` param. Pure JS only — no require/import/fs/net/process (see constellation://docs/guide for full restrictions). IMPORTANT: The `cwd` parameter is required — always set it to the target project directory path.