jarscope 0.1.0

Browse and search JVM library source code by Maven coordinate

Jarscope

Browse and search JVM library source code by Maven coordinate.

Jarscope is an MCP server that gives coding agents fast, reliable access to JVM library APIs. Instead of guessing or searching the filesystem, agents can look up classes, functions, and usage patterns directly in a library's published source code.

Install

uvx jarscope

Configure

Claude Code

claude mcp add jarscope -- uvx jarscope

Claude Desktop / Cursor / etc.

Add to your MCP config:

{
  "mcpServers": {
    "jarscope": {
      "command": "uvx",
      "args": ["jarscope"]
    }
  }
}

Tools

jar_search

Search a library's source code for a regex pattern. Returns matching lines with surrounding context.

jar_search("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.0", "class Json")

jar_read

Read the full source of a specific file in a library.

jar_read("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.0", "commonMain/kotlinx/serialization/json/Json.kt")

jar_list

List files in a library's source JAR, optionally filtered by package path.

jar_list("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.0", prefix="commonMain/kotlinx/serialization/json")

How it works

All three tools take a Maven coordinate (groupId:artifactId:version), which agents can find in build.gradle.kts, pom.xml, or gradle/libs.versions.toml.

Jarscope resolves coordinates to source JARs by checking, in order:

1. Gradle cache (~/.gradle/caches/)
2. Maven local repo (~/.m2/repository/)
3. Maven Central (downloaded and cached locally)

JARs are read directly as ZIP files — no extraction needed. Sources JARs are preferred; javadoc JARs are used as fallback.

License

MIT