lcp

Library Context Protocol

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Documentation: https://zazza123.github.io/lcp

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lcp (Library Context Protocol) is primarly a protocol designed to solve the problem of AI agents not having access to up-to-date library documentation, which leads to hallucinations and inaccurate code generation. The LCP SDK provides tools to scan Python packages, extract API information, and generate LCP-compliant JSON manifests. It also includes features for analyzing documentation coverage and generating missing docstrings using AI.

Installation

pip install lcp

Features

• Scans installed Python packages using inspect and ast modules
• Generates LCP v1 compliant JSON files
• Extracts functions, classes, methods, attributes, and constants
• Parses docstrings for summaries and descriptions
• Extracts type hints from function signatures
• Validates output against LCP JSON schema
• Documentation coverage analysis with JSON/Markdown reports
• Version diff to detect deprecated symbols across releases
• AI-powered docstring generation via OpenAI and Anthropic (lcp[ai])
• Both CLI and Python API interfaces
• MCP server for AI agent integration

Usage

CLI

# Scan a package and output LCP JSON
lcp scan requests -o requests.lcp.json

# Include private symbols
lcp scan mypackage --include-private

# Skip validation
lcp scan mypackage --no-validate

# Start an MCP server for a library manifest
lcp serve requests.lcp.json

Python API

from lcp import scan

# Scan a package
lcp_doc = scan("requests")

# Save to file
lcp_doc.to_file("requests.lcp.json")

# Get as dict
data = lcp_doc.to_dict()

# Include private symbols
lcp_doc = scan("mypackage", include_private=True)

Documentation Coverage

Analyze documentation completeness of a package to identify missing docstrings.

CLI

# Generate coverage report (JSON)
lcp coverage requests -o coverage.json

# Generate coverage report (Markdown)
lcp coverage requests -o coverage.md --format markdown

# Generate both LCP manifest and coverage report in one scan
lcp scan requests -o requests.lcp.json --coverage coverage.json

Python API

from lcp import generate_coverage

# Generate coverage report
report = generate_coverage("requests")

# Check coverage percentage
print(f"Coverage: {report.summary.coverage_percent}%")
print(f"Documented: {report.summary.documented}/{report.summary.total_symbols}")

# List undocumented symbols
for symbol in report.undocumented:
    print(f"  - {symbol.module}:{symbol.entity} ({symbol.kind})")

# Save report
report.to_file("coverage.json")      # JSON format
report.to_file("coverage.md")        # Markdown format

Version Diff

Compare two LCP manifests to detect symbols that were removed between versions and automatically generate deprecation entries.

CLI

# Compare two versions and print the diff report
lcp diff v1.lcp.json v2.lcp.json

# Save the diff report to a file
lcp diff v1.lcp.json v2.lcp.json -o diff.json

# Automatically update the new manifest with deprecation entries
lcp diff v1.lcp.json v2.lcp.json --update

Python API

from lcp import diff_documents, load_lcp_document, update_document

# Load two versions
old = load_lcp_document("v1.lcp.json")
new = load_lcp_document("v2.lcp.json")

# Compare
result = diff_documents(old, new)
print(f"Removed: {len(result.removed)}, Added: {len(result.added)}")

for sid, dep in result.deprecated.items():
    print(f"  {sid}: deprecated in {dep.deprecated_in}")

# Merge deprecations into the new document
updated = update_document(new, result)
updated.to_file("v2.lcp.json")

MCP Server

The SDK includes an MCP (Model Context Protocol) server that exposes LCP manifest data to AI agents. This allows agents to explore library APIs and generate accurate code.

Starting the Server

# Start MCP server for a library
lcp serve requests.lcp.json

# With custom server name
lcp serve numpy.lcp.json --name numpy-docs

MCP Client Configuration

Add to your MCP client configuration (e.g., Claude Desktop):

{
  "mcpServers": {
    "requests-api": {
      "command": "lcp",
      "args": ["serve", "/path/to/requests.lcp.json"]
    }
  }
}

Available MCP Tools

Tool	Description
get_manifest	Get library metadata (name, version, language)
list_modules	List all modules in the library
list_symbols	Browse symbols with optional filtering by module or kind
get_symbol	Get full details for a specific symbol
search_symbols	Find symbols by text search
get_class_members	Get all methods and attributes of a class

Programmatic Usage