Swift — 103 Operations for AI Agents

This page is the canonical reference an AI coding agent uses to refactor, query, and analyze Swift code through the act MCP server. 103 operations available: 29 refactor, 18 query, 42 analysis, 14 verification. 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.

18Query

29Refactor

42Analysis

14Verify

Worked Swift examples

act101 parses Swift with the tree-sitter grammar and edits declarations and expressions as syntax nodes, so a softened try or modernized binding lands on the exact statement it targets. It can replace try! with try?, converting a potentially crashing forced try into an optional result the caller must handle. It can change a let constant binding to a var variable binding at the cursor. And the structure query maps a Swift file's declarations into the same skeleton vocabulary act101 uses for every other language, normalizing a protocol to kind interface alongside languages like TypeScript and Rust. Each example below is the verbatim output of the command shown, run against the file shown. Query outputs are pretty-printed with the timing block omitted.

Soften a forced try

UserService.swift's fetchUser function uses try! to call the network client, which crashes on any failure.

$ act refactor-lang add_try_question_mark --file UserService.swift --params '{"line":2,"column":20,"symbol":"try"}'

Before

func fetchUser() throws -> User {
    let response = try! networkClient.get("/user")
    return response
}

After

func fetchUser() throws -> User {
    let response = try? networkClient.get("/user")
    return response
}

try! becomes try?; response is now an Optional the caller must unwrap or handle.

Make a constant mutable

Calculator.swift's compute function declares result with let, but the value needs to change after it is computed.

$ act refactor-lang convert_let_to_var --file Calculator.swift --params '{"line":2,"column":5}'

Before

func compute() -> Int {
    let result = 10 + 20
    return result
}

After

func compute() -> Int {
    var result = 10 + 20
    return result
}

let result becomes var result; the rest of the function is unchanged.

Query the file's structure as a skeleton

Before touching a file, an agent reads its declaration map instead of the whole source.

$ act query skeleton skel.swift

Before

struct RetryPolicy {
    let maxAttempts: Int
    let baseDelayMs: Int
}

protocol Backoff {
    func delay(forAttempt attempt: Int) -> Int
}

Output

{
    "type": "Skeleton",
    "declarations": [
        {
            "kind": "struct",
            "name": "RetryPolicy",
            "range": {
                "start": {
                    "file": "skel.swift",
                    "line": 1,
                    "column": 1,
                    "byte_offset": 0
                },
                "end": {
                    "file": "skel.swift",
                    "line": 4,
                    "column": 2,
                    "byte_offset": 72
                }
            },
            "name_range": {
                "start": {
                    "file": "skel.swift",
                    "line": 1,
                    "column": 8,
                    "byte_offset": 7
                },
                "end": {
                    "file": "skel.swift",
                    "line": 1,
                    "column": 19,
                    "byte_offset": 18
                }
            }
        },
        {
            "kind": "variable",
            "name": "maxAttempts",
            "range": {
                "start": {
                    "file": "skel.swift",
                    "line": 2,
                    "column": 5,
                    "byte_offset": 25
                },
                "end": {
                    "file": "skel.swift",
                    "line": 2,
                    "column": 25,
                    "byte_offset": 45
                }
            },
            "name_range": {
                "start": {
                    "file": "skel.swift",
                    "line": 2,
                    "column": 9,
                    "byte_offset": 29
                },
                "end": {
                    "file": "skel.swift",
                    "line": 2,
                    "column": 20,
                    "byte_offset": 40
                }
            }
        },
        {
            "kind": "variable",
            "name": "baseDelayMs",
            "range": {
                "start": {
                    "file": "skel.swift",
                    "line": 3,
                    "column": 5,
                    "byte_offset": 50
                },
                "end": {
                    "file": "skel.swift",
                    "line": 3,
                    "column": 25,
                    "byte_offset": 70
                }
            },
            "name_range": {
                "start": {
                    "file": "skel.swift",
                    "line": 3,
                    "column": 9,
                    "byte_offset": 54
                },
                "end": {
                    "file": "skel.swift",
                    "line": 3,
                    "column": 20,
                    "byte_offset": 65
                }
            }
        },
        {
            "kind": "interface",
            "name": "Backoff",
            "range": {
                "start": {
                    "file": "skel.swift",
                    "line": 6,
                    "column": 1,
                    "byte_offset": 74
                },
                "end": {
                    "file": "skel.swift",
                    "line": 8,
                    "column": 2,
                    "byte_offset": 141
                }
            },
            "name_range": {
                "start": {
                    "file": "skel.swift",
                    "line": 6,
                    "column": 10,
                    "byte_offset": 83
                },
                "end": {
                    "file": "skel.swift",
                    "line": 6,
                    "column": 17,
                    "byte_offset": 90
                }
            }
        }
    ]
}

The protocol Backoff surfaces as kind interface, while struct RetryPolicy keeps its own struct kind — act101 normalizes declaration kinds across languages without collapsing Swift's struct/class distinction.

Query

18 query tools, the same on every supported language. Descriptions live in the shared reference: /docs/query-tools.

callers control_flow data_flow definition diagnostics effect_closure effect_summary fix_auto get_type graph import_organize interface mutations references repo_outline skeleton symbols symbols_batch

Refactor

Operation	Description
`add-explicit-type`	Add explicit type annotation to variable declarations
`add-main-actor`	Add @MainActor annotation to type or method for main thread safety
`add-missing-switch-cases`	Add exhaustive pattern matching for enum in switch statement
`add-nonisolated`	Add nonisolated annotation to actor members not using actor state
`add-protocol-sendable`	Add Sendable protocol conformance to thread-safe types
`add-try-question-mark`	Convert force try (try!) to optional try (try?)
`change-signature`	Modify function parameters, return, generics
`convert-class-to-actor`	Convert class to actor for concurrency safety
`convert-for-in-to-for-each`	Convert for-in loop to .forEach closure
`convert-let-to-var`	Convert let binding to var for mutable declarations
`convert-to-sendable`	Add Sendable conformance to thread-safe types
`extract-class`	Extract methods/fields to new class
`extract-computed-property`	Extract getter logic into a computed property
`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), receipt (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-codable-implementation`	Generate Codable conformance with encode/decode
`generate-documentation-comment`	Generate documentation comment stub for public API
`generate-hashable-implementation`	Generate Hashable implementation with hash(into:) and Equatable
`generate-memberwise-init`	Generate memberwise initializer with all properties
`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), receipt (bool)]
`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), receipt (bool)]
`recipe_run`	Run a codemod recipe: declarative match → transform → optional verify across modeled grammars. Preview lists matches; apply writes with optional E7 receipts and all-or-nothing rollback. Returns a per-site report.
`remove-force-unwrap`	Replace force-unwrap with safe unwrapping pattern
`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), receipt (bool)]
`simplify-boolean-literal`	Remove unnecessary == true / == false comparisons
`wrap-if`	Wrap statement in if condition
`wrap-optional`	Wrap expression with optional chaining or optional binding
`wrap-try-catch`	Wrap statement in try-catch block

Analysis

42 analysis tools, the same on every supported language. Descriptions live in the shared reference: /docs/analysis-tools.

analyze_api_diff analyze_chokepoints analyze_clones analyze_clusters analyze_cohesion analyze_conformance analyze_coupling analyze_cycle_risk analyze_cycles analyze_dead_code analyze_depth analyze_entry_points analyze_export analyze_extraction analyze_fan_balance analyze_features analyze_hotspots analyze_impact analyze_inconsistencies analyze_inheritance analyze_interface_bloat analyze_interfaces analyze_layers analyze_orphan_types analyze_patterns analyze_platform_deps analyze_readiness analyze_roles analyze_seams analyze_stability analyze_surface analyze_test_gaps analyze_thickness analyze_type_completeness churn_hotspots co_change_clusters coverage_overlay ownership_map profile_overlay simulate split_module trace_overlay

Verify

14 verify tools, the same on every supported language. Descriptions live in the shared reference: /docs/verification.

bisect_regression gate generate_test_harness scan secret_surface summarize_pr taint_flow unsafe_surface verify_behavioral_equivalence verify_contract_preserved verify_diff_semantics verify_port_parity verify_side_effects verify_test_impact

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