Symbolpeek Mcp

Semantic code intelligence for AI coding agents

Ask for the symbol you need—not the entire file.

.ts   .tsx   .js   .jsx   .rs   .py   .java   .go   .json   .md

Quick start · Language support · Tools · Troubleshooting · Tool reference

SymbolPeek is an MCP server that gives an AI coding agent a symbol-level view of your codebase. Instead of reading a whole file to answer "what does this function do" or "who calls it", the agent asks for one declaration and gets exactly that.

TypeScript and JavaScript are analyzed with the official TypeScript Compiler API. Rust, Python, Java, Go, JSON, and Markdown use embedded Tree-sitter for syntax-level operations.

Quick start

Requirements

• An MCP client. Any stdio MCP client works; [Codex and Claude

Code](#connect-your-client) are documented below.

• Node.js 20 or newer — required for .ts, .tsx, .js, and .jsx

analysis. Rust, Python, Java, Go, JSON, and Markdown work without it.

No clone, Rust toolchain, or manual build is required.

macOS or Linux

curl -fsSL https://raw.githubusercontent.com/pioner92/symbolpeek-mcp/main/scripts/install.sh | sh

Windows PowerShell

irm https://raw.githubusercontent.com/pioner92/symbolpeek-mcp/main/scripts/install.ps1 | iex

The installer verifies the release checksum, installs the package, and then prints the exact command to connect your client. It touches nothing outside its own install directory — no client configuration is modified for you.

What the installer puts where

| Item | macOS / Linux | Windows | | --- | --- | --- | | Package (binary + bundled TypeScript runtime) | ~/.local/share/symbolpeek | %LOCALAPPDATA%\SymbolPeek | | symbolpeek and sym commands | linked into ~/.local/bin | added to the user PATH | | Lifetime statistics (created on first use) | ~/.config/symbolpeek/stats.json (Linux)~/Library/Application Support/SymbolPeek/stats.json (macOS) | %APPDATA%\SymbolPeek\stats.json |

That is the complete list. Connecting the MCP server and installing the [optional agent guidance](#optional-agent-guidance) are separate, explicit steps. See [Uninstall](#uninstall) to remove everything.

To inspect the installer before running it:

curl -fsSL https://raw.githubusercontent.com/pioner92/symbolpeek-mcp/main/scripts/install.sh -o install-symbolpeek.sh
less install-symbolpeek.sh
sh install-symbolpeek.sh

Connect your client

The installer prints these commands with the correct absolute path already filled in. Use the absolute path form — it works regardless of how your client inherits PATH:

# Codex (macOS/Linux)
codex mcp add symbolpeek -- "$HOME/.local/share/symbolpeek/symbolpeek"

# Claude Code (macOS/Linux)
claude mcp add --transport stdio --scope user symbolpeek -- "$HOME/.local/share/symbolpeek/symbolpeek"

# Codex (Windows)
codex mcp add symbolpeek -- "$env:LOCALAPPDATA\SymbolPeek\symbolpeek.exe"

# Claude Code (Windows)
claude mcp add --transport stdio --scope user symbolpeek -- "$env:LOCALAPPDATA\SymbolPeek\symbolpeek.exe"

Restart the client, then verify: codex mcp list, or /mcp inside Claude Code. Use --scope project with Claude Code to enable the server for one project only.

Optional: agent guidance

The tools work as soon as the server is connected. SymbolPeek also ships a short [skill](skills/symbolpeek/SKILL.md) that tells the agent to reach for those tools before opening whole files — without it the model calls them less often.

Install it only for the clients you actually use:

symbolpeek install-skills codex     # writes ~/.codex/skills/symbolpeek
symbolpeek install-skills claude    # writes ~/.claude/skills/symbolpeek
symbolpeek install-skills all       # both

CODEX_HOME and CLAUDE_CONFIG_DIR override those locations. Restart the client afterwards so it discovers the skill.

Try it with a prompt like:

Use the symbolpeek MCP server. List the symbols in the absolute path
/project/src/dashboard.tsx, then read_symbol_context for Dashboard.
After that, find_references for useAuth and go_to_definition for one usage.

Configuration templates are checked in at [config/codex-mcp.toml.example](config/codex-mcp.toml.example) and [config/claude-mcp.json.example](config/claude-mcp.json.example).

What you get

A real request against this repository's own TypeScript worker (src/language/typescript/worker.js, 1,791 lines / 65 KB):

read_symbol(path: ".../src/language/typescript/worker.js",
            symbol: "createProject.collectImports")

{
  "symbol": "createProject.collectImports",
  "kind": "function",
  "file": ".../src/language/typescript/worker.js",
  "lines": { "start": 713, "end": 751 },
  "source": "function collectImports(fileName, collected, visited) {\n  ...\n}",
  "supported": true,
  "analysis": { "backend": "ts-compiler-api", "analysis_level": "syntax", "complete": true }
}

The agent receives 2.0 KB instead of 65 KB — the 39 lines it asked for rather than 1,791 lines it did not. Nested symbols are addressable by qualified name, so the agent never has to read the enclosing function to reach the inner one.

Language support

Every language-aware operation, exactly as reported by get_capabilities:

| Operation | .ts .tsx .js .jsx | .rs | .py .java .go | .json | .md | | --- | :---: | :---: | :---: | :---: | :---: | | read_symbol | ✅ | ✅ | ✅ | ✅ | ✅ | | list_symbols | ✅ | ✅ | ✅ | ✅ | ✅ | | search_symbols | ✅ | ✅ | ✅ | ✅ | ✅ | | get_document_outline | ✅ | ✅ | ✅ | ✅ | ✅ | | find_dependencies | ✅ | ✅¹ | ✅¹ | — | — | | read_symbol_context | ✅ | ✅¹ | ✅¹ | — | — | | find_implementations | ✅ | ✅² | — | — | — | | find_references | ✅ | — | — | — | — | | find_callers | ✅ | — | — | — | — | | find_callees | ✅ | — | — | — | — | | go_to_definition | ✅ | — | — | — | — | | get_type | ✅ | — | — | — | — | | get_diagnostics | ✅ | — | — | — | — | | get_call_hierarchy | ✅ | — | — | — | — | | rename_symbol (writes files) | ✅ | — | — | — | — | | check_safe_to_delete | ✅ | — | — | — | — | | Backend | TypeScript Compiler API | Tree-sitter | Tree-sitter | Tree-sitter | Tree-sitter | | Analysis level | semantic | syntax | syntax | syntax | syntax |

¹ Same-file only — conservative, no cross-file resolution. ² Explicit impl Type and impl Trait for Type blocks. Alias, re-export, and blanket-impl resolution requires rust-analyzer and is not supported.

Unsupported operations fail with an explicit error rather than returning empty results. get_capabilities returns this same matrix at runtime.

Tools

Navigation

| Tool | What it answers | | --- | --- | | read_symbol | "Show me the exact source for this symbol." | | list_symbols | "What are the top-level symbols in this file?" | | search_symbols | "Where is this symbol defined across the workspace?" | | go_to_definition | "Where is the definition behind this usage?" | | read_symbol_context | "Give me this symbol plus its minimal local context." |

Code intelligence

| Tool | What it answers | | --- | --- | | find_references | "Where is this symbol referenced across the project?" | | find_callers | "Which functions or methods call this symbol?" | | find_callees | "Which named targets does this symbol call, including unresolved ones?" | | find_dependencies | "Which local symbols does this symbol depend on?" | | get_call_hierarchy | "What callers and callees surround this symbol?" |

Type analysis

| Tool | What it answers | | --- | --- | | get_type | "What is the inferred type or signature at this location?" | | find_implementations | "Which classes implement this interface or contract?" | | get_document_outline | "What is the nested declaration structure of this file?" | | get_diagnostics | "What TypeScript compiler diagnostics affect this file or symbol?" |

Refactoring

| Tool | What it answers | | --- | --- | | rename_symbol | "Rename this symbol project-wide." Writes files directly. | | check_safe_to_delete | "Is this file referenced from anywhere else, or safe to delete?" |

Discovery and statistics

| Tool | What it answers | | --- | --- | | get_statistics | "How much source context has SymbolPeek avoided?" | | get_capabilities | "Which operations does each language support?" |

Every request shape, option, and response format is documented in the [MCP tool reference](MCP_TOOLS.md).

Where it helps (and where it doesn't)

SymbolPeek does not replace reading files or text search. It replaces the most expensive pattern an agent hits on a real codebase: find a symbol, find everyone who touches it, and understand its type — across import aliases and re-exports.

Where it genuinely saves an agent work and tokens

• One symbol out of a large file. read_symbol / read_symbol_context

return a single declaration instead of a whole file. On large files this is the bulk of the token saving.

• Impact analysis without a grep loop. find_references returns resolved

locations, while find_callers also identifies the enclosing functions in one call. Both use the project's module resolution, including path aliases (@app/...) and barrel re-exports, which text search follows unreliably.

• Resolved types. get_type returns the instantiated signature (for

example useAsync), which text search cannot produce.

• Scoped discovery. search_symbols finds declarations by name and kind

(for example "hooks matching conversation") without the noise of string matches in comments and unrelated code.

Where an agent should still use ordinary tools

• Plain text, comments, small config files, or unsupported files — grep is faster.
• Understanding the full control flow inside one function — just read it.
• Very large monorepos — building a TypeScript program has real latency, so a

targeted grep can win for a single lookup. Rust, Python, Java, Go, and JSON requests never start Node and stay fast regardless of project size.

What makes the results trustworthy

• Parsing, source ranges, type information, and cross-file navigation come from

the TypeScript compiler and its AST. Semantic labels such as hook and react_component are conventions applied on top of that syntax tree, based on naming and JSX usage.

• Cross-file results are only as complete as module resolution allows: with a

valid tsconfig.json they use its configured source set; without one they cover the target file and recursively resolved static imports, exports, and require(...) calls. Compiler options come from the project tsconfig.json.

• Rust, Python, Java, Go, and JSON source ranges and nesting come from

Tree-sitter. Every result carries compact analysis: { backend, analysis_level, complete } trust metadata, where complete: false means the parser recovered from a syntax error.

What gets indexed

TypeScript and JavaScript — function declarations, async functions, generators, and arrow functions; exported and nested functions; React components and hooks; classes and class methods; object methods; interfaces, type aliases, enums and qualified enum members, variables, and constants.

Enum members are addressed by qualified name, for example Screens.PUBLISH_ACKNOWLEDGEMENT. Symbol names are indexed; assigned string values remain literals and require text search.

Rust — functions, structs, unions, enums and variants, traits, impl blocks and methods, modules, constants, statics, type declarations, and macros. Impl methods use qualified names such as Client.send, and trait impl methods use .send.

JSON — object properties are indexed as RFC 6901 JSON Pointers, for example /checkout/errors/payment_failed. Array-valued properties remain single addressable branches instead of expanding every element, which keeps large locale and data files token-efficient. .jsonc and JSON5 are not supported.

Markdown — headings are the symbols, nested by level, and a symbol spans the whole section rather than the heading line. read_symbol with Quick start.Connect your client returns that section alone; on this README that is 839 bytes instead of 20 KB. Both # and underline (setext) headings are indexed, # inside a fenced code block is not, and repeated headings such as Options under several commands get @line:column selectors so each stays addressable. Prose, lists, and code blocks are not indexed separately — this finds sections, not full-text matches.

Using the tools

Absolute file paths are the canonical, most reliable input. Relative paths first use an explicit SYMBOLPEEK_WORKSPACE_ROOT, then filesystem roots supplied by a compatible MCP client; multi-root workspaces resolve only when exactly one root contains the requested path.

Supported files are parsed from their current contents on every request — there is no index to rebuild and no stale cache to invalidate.

Unsupported extensions return { "supported": false }. Missing files, parser failures, and unknown symbols are returned as MCP invalid-parameter errors.

How agents discover the tools

Two mechanisms nudge a model toward targeted reads:

• Server instructions, always on. Every MCP initialization response includes

concise instructions to inspect outlines or search first, then retrieve only the required symbol. This works with any MCP client that exposes server instructions to its LLM — nothing to install.

• The bundled skill, opt-in. [symbolpeek skill](skills/symbolpeek/SKILL.md)

is a stronger, always-loaded hint for Codex and Claude Code, with a trigger description covering code exploration and large JSON locale/configuration files. Install it with [install-skills](#optional-agent-guidance) if you want it.

No MCP server can force a client model to call a tool, but these mechanisms make the intended workflow part of the model's default context. For another agent that consumes neither, copy the short workflow from the bundled skill into that client's global agent instructions.

Statistics

The CLI reports lifetime context-avoidance statistics:

symbolpeek stats
symbolpeek stats --reset

--reset clears lifetime totals only. Session counters belong to the running MCP process and are available through get_statistics().

All numbers compare SymbolPeek with a counterfactual full-source baseline:

• requests — successful semantic calls;
• files avoided — distinct source files represented by each result, summed

across calls (one find_callers request can count several files);

• bytes / lines avoided — full contents of those files minus a compact

serialization of the semantic result;

• estimated token savings — avoided bytes at a fixed ~4 bytes/token

heuristic;

• average context reduction — size-weighted across all requests.

Treat these as directional context-reduction estimates, not exact model-token counts or billing data.

Configuration

Prebuilt binaries detect their bundled TypeScript runtime automatically. These variables are for advanced setups only:

| Variable | Purpose | | --- | --- | | SYMBOLPEEK_WORKSPACE_ROOT | Workspace root used to resolve relative source paths. | | SYMBOLPEEK_ALLOW_CWD_FALLBACK | Allow relative paths to fall back to the process working directory (default true). | | SYMBOLPEEK_TYPESCRIPT_ROOT | Directory containing the TypeScript runtime. | | SYMBOLPEEK_NODE | Explicit Node.js executable for the parser worker. | | SYMBOLPEEK_STATS_PATH | Override the lifetime statistics JSON path. |

For a global MCP installation, do not set SYMBOLPEEK_WORKSPACE_ROOT to a fixed project — use absolute paths, or let the client provide filesystem roots. Set `SYMBOLPEEKALLOWCWD_FALLBACK=fal

…

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: pioner92
• Source: pioner92/symbolpeek-mcp
• License: MIT

Install and usage instructions live in the source repository linked above.