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jCodemunch MCP

Token-efficient code exploration via tree-sitter AST parsing. 25+ languages, 95%+ token savings.

Developer ToolsPythonv1.8.6

Quickstart - https://github.com/jgravelle/jcodemunch-mcp/blob/main/QUICKSTART.md

FREE FOR PERSONAL USE

Use it to make money, and Uncle J. gets a taste. Fair enough? details


Documentation

DocWhat it covers
QUICKSTART.mdZero-to-indexed in three steps
USER_GUIDE.mdFull tool reference, workflows, and best practices
AGENT_HOOKS.mdAgent hooks and prompt policies
ARCHITECTURE.mdInternal design, storage model, and extension points
LANGUAGE_SUPPORT.mdSupported languages and parsing details
CONTEXT_PROVIDERS.mddbt, Git, and custom context provider docs
TROUBLESHOOTING.mdCommon issues and fixes

Cut code-reading token usage by 95% or more

Most AI agents explore repositories the expensive way:

open entire files → skim thousands of irrelevant lines → repeat.

That is not “a little inefficient.” That is a token incinerator.

jCodeMunch indexes a codebase once and lets agents retrieve only the exact code they need: functions, classes, methods, constants, outlines, and tightly scoped context bundles, with byte-level precision.

In retrieval-heavy workflows, that routinely cuts code-reading token usage by 95%+ because the agent stops brute-reading giant files just to find one useful implementation.

TaskTraditional approachWith jCodeMunch
Find a functionOpen and scan large filesSearch symbol → fetch exact implementation
Understand a moduleRead broad file regionsPull only relevant symbols and imports
Explore repo structureTraverse file after fileQuery outlines, trees, and targeted bundles

Index once. Query cheaply. Keep moving. Precision context beats brute-force context.


jCodeMunch MCP

Structured code retrieval for serious AI agents

License MCP Local-first Polyglot jMRI PyPI version PyPI - Python Version

Commercial licenses

jCodeMunch-MCP is free for non-commercial use.

Commercial use requires a paid license.

jCodeMunch-only licenses

Want both code and docs retrieval?

Stop paying your model to read the whole damn file.

jCodeMunch turns repo exploration into structured retrieval.

Instead of forcing an agent to open giant files, wade through imports, boilerplate, comments, helpers, and unrelated code, jCodeMunch lets it navigate by what the code is and retrieve only what matters.

That means:

  • 95%+ lower code-reading token usage in many retrieval-heavy workflows
  • less irrelevant context polluting the prompt
  • faster repo exploration
  • more accurate code lookup
  • less repeated file-scanning nonsense

It indexes your codebase once using tree-sitter, stores structured symbol metadata plus byte offsets into the original source, and retrieves exact implementations on demand instead of re-reading entire files over and over.

Recent releases have also made that retrieval workflow sharper and more useful in real engineering work, with BM25-based symbol search, context bundles, compact search modes, query suggestions for unfamiliar repos, dependency graphs, class hierarchy traversal, blast-radius analysis, multi-symbol bundles, live watch-based reindexing, automatic Claude Code worktree discovery (watch-claude), and benchmark reproducibility improvements.


Real-world results

Independent 50-iteration A/B test on a real Vue 3 + Firebase production codebase — JCodeMunch vs native tools (Grep/Glob/Read), Claude Sonnet 4.6, fresh session per iteration:

MetricNativeJCodeMunch
Success rate72%80%
Timeout rate40%32%
Mean cost/iteration$0.783$0.738
Mean cache creation104,13593,178 (−10.5%)

Tool-layer savings isolated from fixed overhead: 15–25%. One finding category appeared exclusively in the JCodeMunch variant: orphaned file detection via find_importers — a structural query native tools cannot answer without scripting.

Full report: benchmarks/ab-test-naming-audit-2026-03-18.md


Why agents need this

Most agents still inspect codebases like tourists trapped in an airport gift shop:

  • open entire files to find one function
  • re-read the same code repeatedly
  • consume imports, boilerplate, and unrelated helpers
  • burn context window on material they never needed in the first place

jCodeMunch fixes that by giving them a structured way to:

  • search symbols by name, kind, or language
  • inspect file and repo outlines before pulling source
  • retrieve exact symbol implementations only
  • grab a context bundle when surrounding imports matter
  • fall back to text search when structure alone is not enough

Agents do not need bigger and bigger context windows.

They need better aim.


What you get

Symbol-level retrieval

Find and fetch functions, classes, methods, constants, and more without opening entire files.

Faster repo understanding

Inspect repository structure and file outlines before asking for source.

Lower token spend

Send the model the code it needs, not 1,500 lines of collateral damage.

Structural queries native tools can't answer

find_importers tells you what imports a file. get_blast_radius tells you what breaks if you change a symbol. get_class_hierarchy traverses inheritance chains. These are not "faster grep" — they are questions grep cannot answer at all.

Better engineering workflows

Useful for onboarding, debugging, refactoring, impact analysis, and exploring unfamiliar repos without brute-force file reading.

Local-first speed

Indexes are stored locally for fast repeated access.


How it works

jCodeMunch indexes local folders or GitHub repos, parses source with tree-sitter, extracts symbols, and stores structured metadata alongside raw file content in a local index. Each symbol includes enough information to be found cheaply and retrieved precisely later.

That includes metadata like:

  • signature
  • kind
  • qualified name
  • one-line summary
  • byte offsets into the original file

So when the agent wants a symbol, jCodeMunch can fetch the exact source directly instead of loading and rescanning the full file.


Start fast

1. Install it

bash
pip install jcodemunch-mcp

2. Add it to your MCP client

If you’re using Claude Code:

bash
claude mcp add jcodemunch uvx jcodemunch-mcp

3. Tell your agent to actually use it

This matters more than people think.

Installing jCodeMunch makes the tools available. It does not guarantee the agent will stop its bad habit of brute-reading files unless you instruct it to prefer symbol search, outlines, and targeted retrieval. The changelog specifically calls out improved onboarding around this because it is a real source of confusion for first-time users.

A simple instruction like this helps:

markdown
Use jcodemunch-mcp for code lookup whenever available. Prefer symbol search, outlines, and targeted retrieval over reading full files.

Note: For a comprehensive guide on enforcing these rules through agent hooks and prompt policies, see AGENT_HOOKS.md.


Configuration

Settings are controlled by a JSONC config file (config.jsonc) with env var fallbacks for backward compatibility. Defaults are chosen so that a fresh install works without any configuration.

Quick setup

bash
jcodemunch-mcp config --init       # create ~/.code-index/config.jsonc from template
jcodemunch-mcp config              # show effective configuration
jcodemunch-mcp config --check      # validate config + verify prerequisites

--check validates that your config file is well-formed, your AI provider package is installed, your index storage path is writable, and HTTP transport packages are present. Exits non-zero on any failure — useful for CI/CD or first-run scripts.

Config file locations

LayerPathPurpose
Global~/.code-index/config.jsoncServer-wide defaults
Project{project_root}/.jcodemunch.jsoncPer-project overrides

Project config merges over global config — closest to the work wins.

Token-control levers (reduce schema tokens per turn)

Config keyWhat it controlsTypical savings
disabled_toolsRemove tools from schema entirely~100–400 tokens/tool
languagesShrink language enum + gate features~2–86 tokens/turn
meta_fieldsFilter _meta response fields~50–150 tokens/call
descriptionsControl description verbosity~0–600 tokens/turn

See the full template for all available keys. Run jcodemunch-mcp config --init to generate one.

Deprecated env vars (v2.0 will remove)

The following env vars still work but are deprecated. Config file values take priority:

VariableConfig keyDefault
JCODEMUNCH_USE_AI_SUMMARIESuse_ai_summariestrue
JCODEMUNCH_MAX_FOLDER_FILESmax_folder_files2000
JCODEMUNCH_MAX_INDEX_FILESmax_index_files10000
JCODEMUNCH_STALENESS_DAYSstaleness_days7
JCODEMUNCH_MAX_RESULTSmax_results500
JCODEMUNCH_EXTRA_IGNORE_PATTERNSextra_ignore_patterns[]
JCODEMUNCH_CONTEXT_PROVIDERScontext_providerstrue
JCODEMUNCH_REDACT_SOURCE_ROOTredact_source_rootfalse
JCODEMUNCH_STATS_FILE_INTERVALstats_file_interval3
JCODEMUNCH_SHARE_SAVINGSshare_savingstrue
JCODEMUNCH_SUMMARIZER_CONCURRENCYsummarizer_concurrency4
JCODEMUNCH_ALLOW_REMOTE_SUMMARIZERallow_remote_summarizerfalse
JCODEMUNCH_RATE_LIMITrate_limit0
JCODEMUNCH_TRANSPORTtransportstdio
JCODEMUNCH_HOSThost127.0.0.1
JCODEMUNCH_PORTport8901
JCODEMUNCH_LOG_LEVELlog_levelWARNING

AI provider keys (ANTHROPIC_API_KEY, GOOGLE_API_KEY, OPENAI_API_BASE, etc.) and CODE_INDEX_PATH are always read from env vars — they are never placed in config files.

AI provider priority: Anthropic → Gemini → local LLM → signature fallback. The first key that is set wins. jcodemunch-mcp config shows which provider is active.


When does it help?

A common question: does this only help during exploration, or also when the agent is prompted to read a file before editing?

It helps most when editing a specific function. The "read before edit" constraint doesn't require reading the whole file — it requires reading the code. get_symbol_source gives you exactly the function body you're about to touch, nothing else. Instead of reading 700 lines to edit one method, you read those 30 lines.

ScenarioNative tooljCodemunchSavings
Edit one function (700-line file)Read → 700 linesget_symbol_source → 30 lines~95%
Understand a file's structureRead → full contentget_file_outline → names + signatures~80%
Find which file to editGrep many filessearch_symbols → exact matchcomparable
Edit requires whole-file contextRead → full contentget_file_content → full content~0%
"What breaks if I change X?"not possibleget_blast_radiusunique capability

The cases where it doesn't help: edits that genuinely require understanding the entire file (restructuring file-level state, reordering logic that spans hundreds of lines). For those, get_file_content is roughly equivalent to Read. The cases where it helps most are targeted edits — one function, one method, one class — which is the majority of real editing work.


Best for

  • large repositories
  • unfamiliar codebases
  • agent-driven code exploration
  • refactoring and impact analysis
  • teams trying to cut AI token costs without making agents dumber
  • developers who are tired of paying premium rates for glorified file scrolling

New here?

Start with QUICKSTART.md for the fastest setup path.

Then index a repo, ask your agent what it has indexed, and have it retrieve code by symbol instead of reading entire files. That is where the savings start.

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