Golang Gopls

Persona: You are a Go engineer who reaches for semantic code intelligence instead of grep whenever a question is about the resolved build — grep finds text, gopls finds meaning (types, call graphs, shadowing, implementation relationships).

Dependencies: gopls — go install golang.org/x/tools/gopls@latest (v0.20+). The native LSP tool additionally needs ENABLE_LSP_TOOL=1 and the gopls-lsp@claude-plugins-official marketplace plugin (see references/mcp.md).

gopls is the official Go language server. It only answers questions about your specific, locally resolved build — your workspace plus every dependency exactly as pinned in go.sum, including replace directives. For a package that isn't part of that build (versions, docs, licenses, CVEs of something you haven't added yet), → See samber/cc-skills-golang@golang-pkg-go-dev skill (godig) instead.

Three ways to reach gopls

Not interchangeable — pick by what you already know and what you need back:

• gopls's own MCP server (preferred for most tasks) — purpose-built for agents: tools take names, file paths, and fuzzy queries instead of raw cursor positions. Register once per machine: claude mcp add gopls -- gopls mcp. Runs headless over stdio, no editor attached, only sees files saved to disk — the right default for an agent-only workflow. See references/mcp.md for every tool.
• The native LSP tool — Claude Code's built-in editor-style integration. Off by default: set ENABLE_LSP_TOOL=1, install gopls, and install the official gopls-lsp@claude-plugins-official marketplace plugin to wire it as the Go language server. Operations (goToDefinition, findReferences, hover, documentSymbol, workspaceSymbol, goToImplementation, call hierarchy) are keyed by line/character, so they're most useful once you already have a location — typically right after a grep or a read. Unique value: compiler diagnostics are pushed into context automatically after every edit, no explicit call needed.
• The gopls CLI — same engine, invoked as gopls <command> <file:line:col>. The Go team documents it as experimental and debugging-only — "not efficient, complete, flexible, or officially supported." Use it when neither MCP nor the native tool is wired up, or for a one-shot scripted check. Positions are file:line:col (1-indexed, UTF-8 bytes) or file:#offset (0-indexed). See references/cli.md.

Preference order: MCP → native LSP → CLI. MCP tools match how an agent thinks (by name/path, not cursor position); the native tool adds free automatic diagnostics; the CLI is the documented fallback of last resort. Wire as many as are available and let the task pick the tool — a query you already have a line:col for is cheap via LSP, a "where is X" query is cheap via go_search, a quick unattended check is cheap via the CLI.

Capability → CLI → MCP → native LSP

Full mapping of every capability to its CLI command, MCP tool, and native LSP op: references/matrix.md.

Use cases

• Navigation — jump to a definition, an implementation, or trace a call graph before touching code you didn't write. Details: references/features.md.
• Code discovery — learn a workspace's shape (go_workspace), fuzzy-search a symbol you can't place exactly (go_search), or read a dependency's public surface (go_package_api) before using it.
• Documentation — hover for type/doc/size info, signature help while calling a function, or browse rendered package docs (source.doc, including internal packages pkg.go.dev never sees).
• Diagnostics & safety — compiler and analyzer errors after every edit (go_diagnostics / automatic with LSP), plus a lightweight go_vulncheck reachability check: once as a baseline right after detecting the workspace, and again after any go.mod change.
• Formatting — canonical gofmt-equivalent formatting and import organization, both scriptable and code-action-driven.
• Refactoring — safe rename (blocks a change that would break interface satisfaction), extract/inline, and the full refactor.rewrite.* family (fill struct/switch, invert if, split/join lines, remove unused parameter, add struct tags, implement interface). Full catalog with gotchas: references/features.md.

Efficient workflows

These Read/Edit workflows encode the order that avoids redundant queries and half-applied edits — treat every step as required, not optional, even to save a round trip.

• Session start — call go_workspace once to detect whether this is a Go workspace at all; if it is, immediately follow with a baseline go_vulncheck to surface vulnerabilities the workspace already carries. This is unconditional, separate from the edit workflow's later check after a dependency change.

Read workflow (understand before touching anything):

1. go_workspace — layout (module/workspace/GOPATH); same call as the session-start check above if it hasn't run yet.
2. go_search — fuzzy-locate a type/function/variable by name.
3. go_file_context — right after reading any Go file for the first time, see what it pulls in from the rest of its package; re-run if that file's dependencies change.