Nix — 81 Operations for AI Agents
This page is the canonical reference an AI coding agent uses to refactor, query, and analyze Nix code through the act MCP server. 81 operations available: 36 refactor, 15 query, 30 analysis. Each operation is callable from Claude Code, Cursor, Codex, OpenCode, or any MCP-compatible agent host. Click any operation for a stable anchor link suitable for citation.
15Query
36Refactor
30Analysis
Query
| Operation | Description |
|---|---|
callers | Find every call site of a function or method across the codebase. Use to understand who depends on a function before changing its signature. Requires LSP. Params: symbol (string) [, file (string)] |
control_flow | Get a function's control flow — branches, loops, early returns, and basic blocks in execution order. Use to understand complex logic without reading the full implementation. Params: target (string), file (string) |
definition | Jump to definition — find where a symbol is defined given a usage location. Uses abstract syntax trees by default, no LSP required. Params: symbol (string), file (string), line (u32), column (u32) |
diagnostics | Get compiler errors and warnings from the language server. Omit `file` for workspace-wide diagnostics. Pass a file path or directory path to scope results. Requires LSP. |
fix_auto | Auto-fix all deterministic issues in a file, directory, or workspace — missing imports, unused imports, simple type errors. Runs multiple fix-revalidate cycles. Use after making changes to clean up automatically. Requires LSP. Params: none [, file (string), workspace_mode (bool), category (string), commit (bool), max_rounds (u32)] |
get_type | Get the compiler-inferred type of any expression at a position. Use to understand types without reading surrounding code. Requires LSP. Params: file (string), line (u32), column (u32) |
graph | Build a dependency graph from a file — trace what it imports and what imports it, across multiple hops. Use to understand module relationships and change impact before refactoring. Params: file (string) [, depth (u32), direction (string), leaves (bool), order (string)] |
import_organize | Organize, sort, and deduplicate imports in a file. Removes unused imports. Use after adding new code or moving symbols to clean up import blocks automatically. Params: file (string) [, preview (bool)] |
interface | Get a symbol's public API — signatures, types, and docstrings without implementation bodies. Like skeleton but for a single symbol. Use to understand how to call something without reading its internals. Params: target (string), file (string) [, include_private (bool)] |
mutations | Identify side effects — what external state a function reads or writes (globals, file I/O, network, etc.). Use to understand if a function is pure or has hidden dependencies. Params: target (string), file (string) |
references | Find every usage of a symbol across the entire codebase — all files, not just the current one. Use before renaming, refactoring, or deleting to understand full impact. Requires LSP. Params: symbol (string), file (string) |
repo_outline | Get a compressed overview of the entire repository in one call — file tree with languages, line counts, and optionally symbol names per file. Orders of magnitude cheaper than listing directories and reading files individually. Params: none [, path (string), depth (u32), include (glob), exclude (glob), symbols (bool), max_files (u32), relative (bool)] |
skeleton | Get a file's structure — function signatures, class declarations, type definitions — without implementation bodies. Use INSTEAD of reading the full file to understand its API. Typically 5-10x fewer tokens than reading the raw file. Params: file (string) |
symbols | List all symbols (functions, classes, variables, types, constants) defined in a file with their locations and kinds. Use INSTEAD of reading a file when you need to know what's defined in it. Much cheaper than reading the full file. IMPORTANT: file must be a path to a single source file — never a directory or empty string. Params: file (string) |
symbols_batch | Retrieve symbols from multiple files in a single call. Use instead of calling symbols() in a loop — one request instead of N. Params: none [, files (string[]), ids (string[]), kinds (string[])] — provide files or ids |
Refactor
| Operation | Description |
|---|---|
add-inherit-statement | Add an `inherit` statement to an attribute set for given variables |
convert-boolean-to-if | Convert a boolean expression into an if-then-else expression |
convert-if-to-boolean-expression | Simplify `if x then true else false` to just `x` |
convert-import-to-let-binding | Convert an inline `import ./file.nix` into a let binding |
convert-lambda-to-function | Wrap an anonymous lambda in a named let-bound function |
convert-null-coalesce | Convert `x // fallback` merge to an explicit conditional null check |
convert-rec-to-scope | Convert `rec { ... }` to a `let...in` expression |
convert-string-concat-to-interpolation | Transform string concatenation expressions to Nix string interpolation |
convert-to-attr-set-shorthand | Convert attr = attr; bindings to inherit form |
convert-to-string-interpolation | Convert string concatenation (+ operator) to Nix string interpolation |
extract-builtin-call | Extract a repeated builtins function call into a named let binding |
extract-function | Extract an expression into a new named function binding |
extract-function-from-lambda | Convert an anonymous lambda into a named function binding |
extract-let-binding | Extract an expression into a let-in binding |
extract_function | Extract a code selection into a new function — automatically infers parameters, return types, and inserts the call site. Use instead of manually cutting/pasting code. Works without LSP; LSP improves type inference. Params: file (string), new_name (string), start_line (u32), start_column (u32), end_line (u32), end_column (u32) [, preview (bool)] |
extract_variable | Extract an expression into a named variable — inserts the declaration and replaces the expression with the variable name. Works without LSP. Params: file (string), new_name (string), start_line (u32), start_column (u32), end_line (u32), end_column (u32) [, preview (bool)] |
generate-attribute-set | Generate an empty or structured attribute set |
generate-filter-function | Generate a `filter` operation skeleton over a list |
generate-fold-operation | Generate a `builtins.foldl'` operation skeleton |
generate-function | Generate a new function binding skeleton in Nix |
generate-if-then-else | Generate complete if-then-else structure |
generate-let-binding | Generate a let-in expression with variable and body |
generate-map-function | Generate a `map` operation skeleton over a list |
generate-mkderivation | Generate mkDerivation skeleton with common attributes |
generate-test-scaffold | Generate a test expression scaffold for Nix code |
inline | Inline a variable, function, or method — replace every usage with its definition body, then remove the original. The inverse of extract. Works without LSP (single-file); LSP enables cross-file inlining. Params: file (string), symbol (string) [, line (u32), preview (bool)] |
inline-function | Inline a function binding by replacing calls with the body |
inline-variable | Inline a let-bound variable by replacing uses with its definition |
insert_body | Replace a function's implementation body with new code. AST-validated — rejects if the result has parse errors, so you can't accidentally break syntax. Use instead of manual text editing for function rewrites. Params: file (string), symbol (string), code (string) [, commit (bool)] |
move_symbol | Move a function, class, or type to a different file and automatically update all imports across the codebase. Use instead of manually cut/paste + fixing imports. Works without LSP (single-file); LSP enables cross-file import updates. Params: file (string), symbol (string), destination (string) [, preview (bool)] |
organize-imports | Sort and organize import bindings at the top of a Nix file |
remove-unused-parameter | Remove a named parameter from a function's formal set |
remove-unused-variable | Remove a let binding that is never used |
rename | Rename a symbol and automatically update ALL references across the codebase. Safer and faster than find-and-replace — AST-aware, won't rename strings or comments. Works without LSP (single-file); LSP enables cross-file renames. Params: file (string), old_name (string), new_name (string) [, line (u32), column (u32), preview (bool)] |
rename-identifier | Rename a variable, function, or attribute across its scope |
reorder-function-arguments | Reorder formal parameters in a function definition |
Analysis
| Operation | Description |
|---|---|
analyze_chokepoints | Find files that act as critical bottlenecks — high betweenness centrality in the dependency graph (R4). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_clusters | Identify tightly coupled groups of files using community detection. Use to discover natural module boundaries and understand which files change together. Params: none [, granularity (string), min_size (u32), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_cohesion | Measure intra-module cohesion for each file — ratio of internal to total symbol edges (H2). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_coupling | Measure coupling per file — how many files depend on it (afferent) vs how many it depends on (efferent), plus instability and abstractness scores. Use to find the most critical/fragile files. Params: none [, granularity (string), sort (string), threshold (f64), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_cycle_risk | Score each circular dependency cycle by its external risk surface (R6 circular risk zones analysis). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_cycles | Find circular dependency chains in the codebase. Use to identify import cycles that cause build issues or indicate architecture problems. Params: none [, granularity (string), max_length (u32), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_dead_code | Find dead code — functions, classes, and types that are never referenced from any entry point. Use before cleanup to safely identify what can be deleted. Params: none [, entry (string[]), granularity (string), include_tests (bool), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_depth | Compute longest transitive dependency chain per file (S4 dependency depth analysis). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_entry_points | Detect entry points: main functions, HTTP routes, CLI commands, event listeners, test files (S5). Params: none [, include (string[]), exclude (string[])]. |
analyze_export | Export the full semantic graph (files, symbols, dependencies) in JSON, DOT (Graphviz), or CSV format. Use for visualization or external analysis. Params: none [, format (string), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_extraction | Score clusters for service or package extraction viability (M2 extraction candidates analysis). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_fan_balance | Compute fan-in/fan-out imbalance for migration ordering guidance (M6 fan balance analysis). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_features | Inventory language-specific AST features used in the codebase — async, generics, decorators, etc. (M3). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_hotspots | Rank files by composite complexity score — max cyclomatic complexity, statement count, nesting depth (H1). Params: none [, top_n (u32), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_impact | Compute change impact for a target file — finds all files directly and transitively depending on it (R1). Params: target (string) [, max_depth (u32), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_inconsistencies | Detect inconsistent abstractions — sibling files in the same directory that diverge from the group's structural pattern (H5). Params: none [, include (string[]), exclude (string[])]. |
analyze_inheritance | Detect tangled inheritance — deep hierarchies (>N levels) and diamond inheritance (H6). Params: none [, include (string[]), exclude (string[])]. |
analyze_interface_bloat | Detect interface bloat — files where the public API is disproportionately large relative to implementation (H3). Params: none [, include (string[]), exclude (string[])]. |
analyze_interfaces | Map cross-module interfaces — symbols that cross directory-module boundaries, ranked by interface width (M4). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_layers | Detect architectural layers from directory names and find dependency direction violations (S1+S2). Params: none [, detect_only (bool), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_orphan_types | Find type definitions used exclusively outside their defining directory (H4 orphan types analysis). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_patterns | Find code smells — god functions, deep nesting, high coupling, and other structural issues. Use to identify refactoring targets or assess code quality. Params: none [, tier (string), pattern (string), file (string), severity (string), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_platform_deps | Detect platform-specific API usage by scanning imports (M5 platform dependencies analysis). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_readiness | Compute migration readiness scores per file — composite of complexity, coupling, porting blockers (M1). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_roles | Classify files by architectural role: entry point, routing, business logic, data access, config, test, utility, types, generated (S3). Params: none [, include (string[]), exclude (string[])]. |
analyze_seams | Find the natural boundaries between file clusters — the narrowest points where groups of files communicate. Use to identify where to split modules or add API boundaries. Params: none [, min_cluster_size (u32), max_seam_width (u32), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_stability | Compute stability index (R2) and detect stable dependency violations (R3) — flags edges where stable modules depend on unstable ones. Params: none [, index_only (bool), include (string[]), exclude (string[])]. |
analyze_surface | Measure API surface area — count exposed functions, types, and complexity at a module boundary. Use to assess whether an API is too large or leaky. Params: none [, boundary (string), files (string), include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_test_gaps | Detect source files with no or partial test coverage based on graph import analysis (R5). Params: none [, include (string[]), exclude (string[])]. Use include/exclude to restrict the scan scope (e.g. include=["crates"], exclude=["corpus"]). |
analyze_type_completeness | Analyze type boundary completeness — detect 'any' types, untyped parameters, missing return types at exported function boundaries (M7). Params: none [, include (string[]), exclude (string[])]. |