COBOL — 122 Operations for AI Agents
This page is the canonical reference an AI coding agent uses to refactor, query, and analyze COBOL code through the act MCP server. 122 operations available: 48 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.
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Worked COBOL examples
act101 reads a COBOL program by its divisions: the skeleton reports each WORKING-STORAGE data item, group levels, elementary PIC items and level-88 condition names alike, as a variable, and each PROCEDURE DIVISION paragraph as a function. consolidate_paragraphs merges a paragraph into the one before it only when nothing but a fall-through from that paragraph reaches it, so the program runs the same statements in the same order. query complexity scores a program by its decision points. 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.
Merge a fall-through paragraph into the one above it
counter.cob's MAIN-PARA zeroes WS-COUNTER and falls through into REPORT-PARA, which displays it and stops the run; nothing performs REPORT-PARA by name.
$ act refactor-lang consolidate_paragraphs --file counter.cob --params '{"source_paragraph":"REPORT-PARA","target_paragraph":"MAIN-PARA"}'Before
IDENTIFICATION DIVISION.
PROGRAM-ID. CONSOLIDATE-DEMO-D.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-COUNTER PIC 9(3).
PROCEDURE DIVISION.
MAIN-PARA.
MOVE ZEROS TO WS-COUNTER.
REPORT-PARA.
DISPLAY "Count: " WS-COUNTER.
STOP RUN.After
IDENTIFICATION DIVISION.
PROGRAM-ID. CONSOLIDATE-DEMO-D.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-COUNTER PIC 9(3).
PROCEDURE DIVISION.
MAIN-PARA.
MOVE ZEROS TO WS-COUNTER.
DISPLAY "Count: " WS-COUNTER.
STOP RUN.The REPORT-PARA. header is removed and its DISPLAY and STOP RUN statements now end MAIN-PARA; the data division is unchanged.
Outline a program's data items and paragraphs
OVERDUE.cob computes a library fine: a WS-LOAN group holds the days late and a member type with two level-88 conditions, and MAIN-PARA performs COMPUTE-FINE THRU CAP-FINE.
$ act query skeleton OVERDUE.cobBefore
IDENTIFICATION DIVISION.
PROGRAM-ID. OVERDUE-FINES.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-LOAN.
05 WS-DAYS-LATE PIC 9(3) VALUE 12.
05 WS-MEMBER-TYPE PIC X VALUE "S".
88 IS-STUDENT VALUE "S".
88 IS-STAFF VALUE "T".
01 WS-FINE-CENTS PIC 9(5) VALUE ZERO.
PROCEDURE DIVISION.
MAIN-PARA.
PERFORM COMPUTE-FINE THRU CAP-FINE.
DISPLAY "Fine in cents: " WS-FINE-CENTS.
STOP RUN.
COMPUTE-FINE.
IF IS-STUDENT
COMPUTE WS-FINE-CENTS = WS-DAYS-LATE * 10
ELSE
COMPUTE WS-FINE-CENTS = WS-DAYS-LATE * 25
END-IF.
CAP-FINE.
IF WS-FINE-CENTS > 500
MOVE 500 TO WS-FINE-CENTS
END-IF.Output
{
"type": "Skeleton",
"declarations": [
{
"kind": "variable",
"name": "WS-LOAN",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 5,
"column": 8,
"byte_offset": 127
},
"end": {
"file": "OVERDUE.cob",
"line": 5,
"column": 18,
"byte_offset": 137
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 5,
"column": 11,
"byte_offset": 130
},
"end": {
"file": "OVERDUE.cob",
"line": 5,
"column": 18,
"byte_offset": 137
}
}
},
{
"kind": "variable",
"name": "WS-DAYS-LATE",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 6,
"column": 11,
"byte_offset": 149
},
"end": {
"file": "OVERDUE.cob",
"line": 6,
"column": 50,
"byte_offset": 188
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 6,
"column": 14,
"byte_offset": 152
},
"end": {
"file": "OVERDUE.cob",
"line": 6,
"column": 26,
"byte_offset": 164
}
}
},
{
"kind": "variable",
"name": "WS-MEMBER-TYPE",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 7,
"column": 11,
"byte_offset": 200
},
"end": {
"file": "OVERDUE.cob",
"line": 7,
"column": 48,
"byte_offset": 237
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 7,
"column": 14,
"byte_offset": 203
},
"end": {
"file": "OVERDUE.cob",
"line": 7,
"column": 28,
"byte_offset": 217
}
}
},
{
"kind": "variable",
"name": "IS-STUDENT",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 8,
"column": 14,
"byte_offset": 252
},
"end": {
"file": "OVERDUE.cob",
"line": 8,
"column": 42,
"byte_offset": 280
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 8,
"column": 17,
"byte_offset": 255
},
"end": {
"file": "OVERDUE.cob",
"line": 8,
"column": 27,
"byte_offset": 265
}
}
},
{
"kind": "variable",
"name": "IS-STAFF",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 9,
"column": 14,
"byte_offset": 295
},
"end": {
"file": "OVERDUE.cob",
"line": 9,
"column": 42,
"byte_offset": 323
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 9,
"column": 17,
"byte_offset": 298
},
"end": {
"file": "OVERDUE.cob",
"line": 9,
"column": 25,
"byte_offset": 306
}
}
},
{
"kind": "variable",
"name": "WS-FINE-CENTS",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 10,
"column": 8,
"byte_offset": 332
},
"end": {
"file": "OVERDUE.cob",
"line": 10,
"column": 52,
"byte_offset": 376
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 10,
"column": 11,
"byte_offset": 335
},
"end": {
"file": "OVERDUE.cob",
"line": 10,
"column": 24,
"byte_offset": 348
}
}
},
{
"kind": "function",
"name": "MAIN-PARA",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 12,
"column": 8,
"byte_offset": 412
},
"end": {
"file": "OVERDUE.cob",
"line": 12,
"column": 18,
"byte_offset": 422
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 12,
"column": 8,
"byte_offset": 412
},
"end": {
"file": "OVERDUE.cob",
"line": 12,
"column": 17,
"byte_offset": 421
}
}
},
{
"kind": "function",
"name": "COMPUTE-FINE",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 16,
"column": 8,
"byte_offset": 550
},
"end": {
"file": "OVERDUE.cob",
"line": 16,
"column": 21,
"byte_offset": 563
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 16,
"column": 8,
"byte_offset": 550
},
"end": {
"file": "OVERDUE.cob",
"line": 16,
"column": 20,
"byte_offset": 562
}
}
},
{
"kind": "function",
"name": "CAP-FINE",
"range": {
"start": {
"file": "OVERDUE.cob",
"line": 22,
"column": 8,
"byte_offset": 745
},
"end": {
"file": "OVERDUE.cob",
"line": 22,
"column": 17,
"byte_offset": 754
}
},
"name_range": {
"start": {
"file": "OVERDUE.cob",
"line": 22,
"column": 8,
"byte_offset": 745
},
"end": {
"file": "OVERDUE.cob",
"line": 22,
"column": 16,
"byte_offset": 753
}
}
}
]
}The group WS-LOAN, its two 05 items, the conditions IS-STUDENT and IS-STAFF and the separate WS-FINE-CENTS are all variables; the three paragraphs are functions, named without their trailing period.
Score a program's decision points
The same program branches twice: COMPUTE-FINE picks a per-day rate on IS-STUDENT, and CAP-FINE caps the fine at 500 cents.
$ act query complexity OVERDUE.cobBefore
IDENTIFICATION DIVISION.
PROGRAM-ID. OVERDUE-FINES.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-LOAN.
05 WS-DAYS-LATE PIC 9(3) VALUE 12.
05 WS-MEMBER-TYPE PIC X VALUE "S".
88 IS-STUDENT VALUE "S".
88 IS-STAFF VALUE "T".
01 WS-FINE-CENTS PIC 9(5) VALUE ZERO.
PROCEDURE DIVISION.
MAIN-PARA.
PERFORM COMPUTE-FINE THRU CAP-FINE.
DISPLAY "Fine in cents: " WS-FINE-CENTS.
STOP RUN.
COMPUTE-FINE.
IF IS-STUDENT
COMPUTE WS-FINE-CENTS = WS-DAYS-LATE * 10
ELSE
COMPUTE WS-FINE-CENTS = WS-DAYS-LATE * 25
END-IF.
CAP-FINE.
IF WS-FINE-CENTS > 500
MOVE 500 TO WS-FINE-CENTS
END-IF.Output
{
"type": "Complexity",
"score": 3,
"details": "Base complexity: 1, +1 if_header, +1 if_header"
}The score of 3 is the base of 1 plus one for each IF header; the ELSE branch and the PERFORM … THRU range add nothing.
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-comments |
Add or improve comments for clarity |
add-cross-field-validation |
Add consistency checks across fields |
add-data-validation |
Add input validation for critical data items |
add-error-handling |
Wrap file operations in error handling |
add-file-status-checks |
Add FILE STATUS checking after file operations |
add-null-check |
Add SPACES/ZEROS check before use |
change-signature |
Modify USING clause parameters |
change-visibility |
Convert between WORKING-STORAGE and LOCAL-STORAGE |
consolidate-paragraphs |
Merge a fall-through paragraph into its predecessor |
convert-evaluate-to-if |
Convert EVALUATE to IF/ELSE-IF chain |
convert-if-to-evaluate |
Convert IF chain to EVALUATE |
convert-perform-until-to-times |
Convert PERFORM UNTIL to PERFORM TIMES |
convert-perform-varying |
Convert between PERFORM VARYING forms |
convert-procedure-forms |
Convert between PERFORM THRU and single-paragraph PERFORM |
convert-string-forms |
Convert between STRING/UNSTRING and MOVE |
convert-variable-mutability |
Convert between VALUE and INITIALIZE-based initialization |
extract-constant |
Define constant using 88-level condition |
extract-function |
Extract code into new paragraph or section |
extract-validation-paragraph |
Extract data validation into reusable paragraph |
extract-variable |
Extract value to data item in WORKING-STORAGE |
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-accessors |
Generate MOVE-based getter/setter paragraphs |
generate-constructor |
Generate INITIALIZE paragraph |
generate-equals |
Generate equality check paragraph |
generate-hash |
Generate hash/hashCode method |
generate-impl |
Generate paragraph skeleton |
generate-tests |
Generate test wrapper or harness |
generate-to-string |
Generate DISPLAY representation |
import-add |
Add COPY statement for copybook |
import-alias |
Create COPY alias with REPLACING |
import-organize |
Sort and organize COPY statements |
import-remove |
Remove an unused COPY statement |
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: it walks the workspace for references and refuses, naming the file, when it cannot read every candidate file; a language server makes the reference set exact. Params: file (string), symbol (string) [, line (u32), column (u32), preview (bool), receipt (bool)]. line alone resolves the symbol's one declaration on that line (refused when the line declares none or several of the name); line + column pinpoints its name |
inline |
Inline paragraph at call sites |
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)] |
introduce-parameter |
Add parameter to USING clause |
move |
Move data item or paragraph to different location |
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: it walks the workspace for references and refuses, naming the file, when it cannot read every candidate file; a language server makes the reference set exact. 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-goto-usage |
Convert GO TO to PERFORM or structured EVALUATE |
remove-unreachable-code |
Remove code after an unconditional GO TO |
remove-unused-paragraphs |
Remove unreferenced paragraphs |
remove-unused-variables |
Remove unreferenced data definitions |
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: it renames across the workspace and refuses, naming the file, when it cannot read every candidate file; a language server makes the reference set exact. Params: file (string), old_name (string), new_name (string) [, line (u32), column (u32), preview (bool), receipt (bool)]. line alone resolves the symbol's one declaration on that line (refused when the line declares none or several of the name); line + column pinpoints its name |
rename |
Rename identifier and all references |
rename-paragraph |
Rename paragraph and update all references |
simplify-conditionals |
Simplify nested IF statements |
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