Lean LSP MCP

MCPOpen SourceMIT60.3

by oOo0oOo • NLP & LLM

An MCP server that enables agentic interaction with the Lean theorem prover via the Language Server Protocol, providing tools for diagnostics, goals, search and automated proof assistance.

Example Use Cases

1
Inspect Lean files, retrieve diagnostics, hover documentation, and the current proof goal at a precise source location.
2
Search for relevant theorems and definitions using local project search (rg), loogle, leansearch, or premise/hammer-style remote services to find premises for a goal.
3
Run or compile Lean snippets, try multiple proof attempts, and rebuild/restart the Lean LSP server within a project workflow.

Description

lean-lsp-mcp exposes Lean LSP functionality and a set of local and external search tools (leansearch, loogle, premise/hammer integrations, local ripgrep search) through the Model Context Protocol so LLM agents can inspect files, get goals, hover info, run snippets, and query relevant theorems. It supports multiple transports (stdio, streamable-http, sse), environment variable configuration, IDE integrations (VSCode, Cursor, Claude Code) and project build/restart tooling. The server is MIT-licensed and positioned as a beta research tool to assist automated proof development and Lean project analysis.

Capabilities(21 total)

Tools (21)

lean_build

Build the Lean project and restart LSP. Use only if needed (e.g. new imports).

lean_project_path:anyclean:booleanoutput_lines:integer

lean_file_outline

Get imports and declarations with type signatures. Token-efficient.

file_path:string*max_declarations:any

lean_diagnostic_messages

Get compiler diagnostics (errors, warnings, infos) for a Lean file.

file_path:string*start_line:anyend_line:anydeclaration_name:anyinteractive:boolean

lean_goal

Get proof goals at a position. MOST IMPORTANT tool - use often! Omit column to see goals_before (line start) and goals_after (line end), showing how the tactic transforms the state. "no goals" = proof complete.

file_path:string*line:integer*column:any

lean_term_goal

Get the expected type at a position.

file_path:string*line:integer*column:any

Quick Actions

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Security

Scanned 2 month(s) ago

Risk Level

MINIMAL

Read-only data retrieval, no side effects

Trust Score

B70/100

10/17 checks passed

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Quick Stats

Service TypeMCP

Pricing ModelFree

Capabilities21 Tools / 0 Prompts / 0 Resources

OwneroOo0oOo

CategoryNLP & LLM

DependenciesStandalone

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