Pkgsite Mcp

pkgsite-mcp

[](https://pkg.go.dev/github.com/sv-tools/pkgsite-mcp)

An MCP server that exposes the pkg.go.dev API as tools, so an LLM can search for Go packages and inspect modules, packages, symbols, importers, and vulnerabilities — without downloading anything.

It wraps the pkg.go.dev v1beta HTTP API (see the announcement), the same API used by the pkgsite-cli reference client. The server speaks MCP over stdio, the transport used by Claude Code, Claude Desktop, and most IDE integrations.

Install

go install github.com/sv-tools/pkgsite-mcp@latest

This installs the pkgsite-mcp binary into $(go env GOPATH)/bin.

Use with Claude Code

claude mcp add pkgsite --scope=user -- pkgsite-mcp

Use with Codex

codex mcp add pkgsite -- pkgsite-mcp

Use with Claude Desktop / other MCP clients

Add the server to your client's MCP config (for Claude Desktop, claude_desktop_config.json):

{
  "mcpServers": {
    "pkgsite": {
      "command": "pkgsite-mcp"
    }
  }
}

Use the absolute path to the binary if it is not on your PATH.

Tools

| Tool | Description | |------------------------|--------------------------------------------------------------------------------------------------| | search | Search pkg.go.dev for packages by name or keywords. | | get_package | Package details: module, version, synopsis, and optionally rendered docs, imports, and licenses. | | get_package_symbols | Exported symbols (functions, types, methods, vars, consts) of a package. | | get_imported_by | Packages from other modules that import a given package (reverse deps; same-module excluded). | | get_module | Module details: version, commit time, repo URL, and optionally README and licenses. | | list_module_versions | Available versions of a module. | | list_module_packages | Packages contained in a module at a version. | | get_vulnerabilities | Known vulnerabilities (Go vuln database) for a module path and version. |

Endpoints that can return many results (search, get_package_symbols, get_imported_by, list_module_versions, list_module_packages, get_vulnerabilities) accept an optional limit and a token. When a response includes a non-empty nextPageToken, pass it back as token to fetch the next page.

Prompts

The server also exposes guided, multi-tool workflows as MCP prompts:

| Prompt | Arguments | Description | |-----------------|---------------------|-------------------------------------------------------------------------------------------------------| | audit_module | module, version | Check a module for known vulnerabilities and whether it is up to date. | | audit_project | path | Audit a Go project's dependencies for vulnerabilities, unmaintained modules, and unused requirements. | | find_package | need | Search for packages that meet a need and recommend one. |

Agent skills (Codex and other non–Claude-Code agents)

MCP prompts are surfaced only by Claude Code. For agents that consume filesystem agent skills instead — such as OpenAI Codex — the same workflows are mirrored as SKILL.md files under [skills/](skills). Install them into your agent's skills folder with pkgsite-mcp install-skills (the binary bundles them); see [skills/README.md](skills/README.md) for details.

Flags

| Flag | Default | Description | |--------------|----------------------|--------------------------------------------------| | -server | https://pkg.go.dev | pkg.go.dev API server URL. | | -timeout | 30s | HTTP request timeout. | | -retries | 2 | Retry attempts for transient failures (429/5xx). | | -cache-ttl | 5m | Response cache TTL; 0 disables caching. | | -version | | Print the version and exit. |

Transient failures (network errors and HTTP 429/5xx) are retried with exponential backoff, honoring any Retry-After header. Successful responses are cached in memory for -cache-ttl, keyed by request URL, to avoid refetching during multi-step exploration.

Development

go build ./...
go test ./...
go vet ./...

Layout:

• internal/pkgsite — a small, dependency-free client for the pkg.go.dev

v1beta API.

• internal/server — registers each API endpoint as an MCP tool.
• internal/server/docs — embedded Markdown for the tool and prompt

descriptions and the server instructions, so the prose can be edited without touching Go.

• main.go — CLI entrypoint; runs the server over stdio.

License

See [LICENSE](LICENSE).

Source & license

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

• Author: sv-tools
• Source: sv-tools/pkgsite-mcp
• License: MIT

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