Hechtcarmel Jetbrains Index MCP Plugin Jetbrains Index MCP Plugin

IDE Index MCP - Agent Guide

The IDE Index MCP server exposes JetBrains IDE indexing and refactoring capabilities. These tools provide semantic code understanding superior to text-based search/replace.

Two IntelliJ MCPs — routing rule

If both mcp__intellij-index__* (this plugin) and mcp__intellij__* (JetBrains built-in) are available, they are not interchangeable:

Always use mcp__intellij-index__ for code intelligence. At least one project must be open in IntelliJ — if no project is open, ask the user to open one or use ide_open_project (disabled by default; enable in Settings → Index MCP Server). Do not fall back to bash for semantic operations — IDE tools understand types, references, and inheritance; grep does not.

Core Rule

Always prefer IDE MCP tools over built-in tools (grep, find, sed, read) for semantic code operations. IDE tools understand code structure, types, inheritance, and references. Built-in tools only see text.

When to Use IDE Tools vs Built-In Tools

Pre-Flight Check

Before using any IDE tool that requires smart mode, check IDE readiness:

ide_index_status -> if isDumbMode: true, wait a few seconds and retry

Most tools require smart mode (IDE finished indexing). Tools that work in dumb mode: ide_index_status, ide_sync_files, ide_reformat_code, ide_open_file, ide_get_active_file.

If results seem incomplete or missing

Do NOT fall back to bash, grep, or the built-in mcp__intellij__* MCP. If a tool returns "dumb mode" or "index not ready":

1. Call ide_index_status — if isDumbMode: true, keep calling every 10s until it flips to false.
2. Then retry the exact same tool call with the same arguments.
3. If smart mode but results seem sparse, call ide_sync_files then retry.
4. Only if all retries still return empty results should you consider that the symbol genuinely does not exist.

The built-in mcp__intellij__* MCP is not a fallback for mcp__intellij-index__* — they serve different purposes and the built-in one cannot do semantic code search. Trying it when the index is in dumb mode will also fail. Always wait for smart mode and retry with mcp__intellij-index__*.

"Index may be stale" and "dumb mode" are transient — always resolve by waiting and retrying, never by switching to bash.

File Sync Rule

If you created or modified files outside the IDE (via Write/Edit tools) and an IDE search tool returns incomplete/missing results, call ide_sync_files first, then retry.

{ "paths": ["src/new_file.java", "src/modified_file.java"] }

Omit paths to sync the entire project.

Parameter Rules

1. Line and column are 1-based (first line = 1, first column = 1)
2. Project file paths are relative to project root (e.g., src/main/java/App.java, NOT absolute paths). If an IDE tool returns a dependency/library file, keep the returned absolute path or jar:// URL unchanged when passing it back to read-only navigation tools or ide_read_file
3. Column must point to the symbol name, not whitespace or punctuation. For public void myMethod(), column should land on m of myMethod. For dotted expressions like json.dumps() or os.path.join(), put the column on the member token (dumps, join) when you want the member definition rather than the module/package.
4. project_path is only needed for multi-project workspaces. Omit for single-project setups. When needed, use the absolute path to the project root.
5. Use built-in search scope intentionally: ide_find_references, ide_find_implementations, ide_type_hierarchy, ide_call_hierarchy, ide_find_class, ide_find_file, and ide_find_symbol accept scope. Use project_files for the default project-only view, project_and_libraries when dependency code matters, project_production_files to stay out of tests, and project_test_files when you want test-only results.

Tool Selection by Task

"I need to understand how X is used"

1. ide_find_references - all call sites, field accesses, imports
2. ide_call_hierarchy with direction: "callers" - full call chain upward

"I need to understand what X is"

1. ide_find_definition - jump to source
2. ide_type_hierarchy - inheritance chain
3. ide_find_super_methods - what interface/base method it implements

"I need to find a class/file/symbol"

1. ide_find_class - classes by name (CamelCase: USvc finds UserService)
2. ide_find_file - files by name
3. ide_search_text - exact word occurrences across project

"I need to refactor"

1. ide_refactor_rename - rename symbol + all references atomically
2. ide_move_file - move file and let the IDE apply semantic updates when that language/backend supports them
3. ide_refactor_safe_delete - delete with usage checking (Java/Kotlin only)
4. ide_reformat_code - apply project code style (disabled by default)

"I need to check for problems"

1. ide_diagnostics - compiler errors, warnings, quick fixes

"I need to find implementations of an interface"

1. ide_find_implementations - cursor on interface/abstract class/method

"I need to trace call chains"

1. ide_call_hierarchy with direction: "callers" - who calls this?
2. ide_call_hierarchy with direction: "callees" - what does this call?

Common Mistakes to Avoid

1. Using grep instead of ide_find_references: Grep finds text, not semantic usages. Misses aliased imports, includes false positives from comments/strings.

2. Using sed/replace instead of ide_refactor_rename: Text replacement breaks code. IDE rename updates all references, getters/setters, overrides, test classes, imports.

3. Using mv/git mv instead of ide_move_file: File system moves bypass IDE move semantics. ide_move_file can preserve IDE-managed package/namespace/reference updates when the active language backend supports them.

4. Forgetting to check index status: If IDE is indexing (dumb mode), most tools error. Check ide_index_status first if a tool fails unexpectedly.

5. Using 0-based line/column: All IDE tools use 1-based. Line 5 in file = line: 5.

6. Passing absolute project file paths: Use relative paths for project files. src/main/App.java, not /Users/me/project/src/main/App.java.

7. Rewriting plugin-returned library paths: If a search or read tool returns an absolute path or jar:// URL for a dependency/library file, pass that path back unchanged to read-only navigation tools or ide_read_file.

8. Not syncing after external file changes: After creating files via Write tool, call ide_sync_files before searching.

9. Assuming regex is the default in ide_search_text: Regex requires "regex": true; otherwise the tool uses the faster exact-word index.

10. Using ide_find_class for methods/functions: It searches classes only. Use ide_search_text for a quick word lookup.

Lifecycle Management

When multiple projects are open simultaneously, the lifecycle manager automatically sleeps and wakes them based on window focus and MCP activity. Projects enroll automatically on first MCP use — no setup required.

States: active (full IDE) → background (Power Save on) → dormant (editors closed, PSI cache freed) → closed (fully unloaded). Projects auto-reopen transparently when an MCP tool targets a closed project.

ide_project_status is the read-only entry point — enabled by default. Use it to see all open and managed projects and their current modes.

All lifecycle action tools are disabled by default:

ide_enroll_all_projects, ide_get_project_modes, ide_lifecycle_log, ide_release_all_projects, ide_release_project, ide_set_all_project_modes, ide_set_lifecycle_log_file, ide_set_project_mode

Disabled-by-Default Tools

These tools exist but are disabled by default. They are omitted from tools/list, and direct tools/call requests are rejected until the user enables them in IDE settings (Settings > Tools > Index MCP Server):

ide_build_project, ide_close_project, ide_convert_java_to_kotlin, ide_enroll_all_projects, ide_file_structure, ide_find_symbol, ide_get_active_file, ide_get_project_modes, ide_import_modules, ide_install_plugin, ide_lifecycle_log, ide_open_file, ide_open_project, ide_optimize_imports, ide_read_file, ide_reformat_code, ide_release_all_projects, ide_release_project, ide_reload_project, ide_restart, ide_set_all_project_modes, ide_set_lifecycle_log_file, ide_set_power_save_mode, ide_set_project_mode

Note: ide_restart terminates the MCP connection — reconnect your client after calling it. Note: ide_close_project refuses to close the last open project; ide_open_project requires an absolute path and may take up to timeoutSeconds (default 600) while the project indexes.

Detailed Tool Parameters

For complete parameter reference with types, defaults, and return formats, see tools-reference.md.

Source: hechtcarmel/jetbrains-index-mcp-plugin — distributed by TomeVault.