Golang Pkg Go Dev

golang-pkg-go-dev

Dependencies: godig — go install github.com/samber/godig/cmd/godig@latest (or use a registered godig MCP server / the hosted instance instead).

godig queries the pkg.go.dev API. Use it to answer questions about Go packages and modules: docs, symbols, versions, importers and vulnerabilities. It works as a CLI and as an MCP server. All operations are read-only and need no authentication.

When to use this skill

Trigger on questions like:

• "What versions of github.com/samber/lo are available?"
• "Does golang.org/x/text have known vulnerabilities?"
• "Show me the docs / symbols for package X."
• "Which packages import X?"
• "Search Go packages for Y."

Setup

Install

go install github.com/samber/godig/cmd/godig@latest

Register the MCP server (optional)

godig mcp runs over stdio by default, or streamable HTTP with --transport http.

stdio (the client launches godig on demand):

claude mcp add pkg-go-dev -- godig mcp

streamable HTTP (shared server at /mcp, default :8080):

godig mcp --transport http --addr :8080
claude mcp add --transport http pkg-go-dev http://localhost:8080/mcp

Hosted instance (no install needed) — a public server runs at https://godig.samber.dev/mcp:

claude mcp add --transport http pkg-go-dev https://godig.samber.dev/mcp

The CLI and the MCP server expose the same operations under matching names. Prefer the CLI when godig is installed; the hosted instance is a fallback when it is not.

Commands

Global flags (all commands): -o/--output table|json|raw|md (default table — pass -o md for chat), --base-url (pkg.go.dev API), --vuln-base-url (Go vulnerability database, consulted by vulns and overview), --timeout, --log-level debug|info|warn|error|off. All are also settable via GODIG_* env vars.

When godig runs as an MCP server, each data command above is exposed as an operation of the same name.

Exit codes: 0 success, 1 runtime error (network, package not found), 2 usage error — a missing/invalid argument or flag (e.g. a non-positive --limit), or a command group invoked with no subcommand (godig package). Check for 2 to tell a malformed call apart from a failed lookup.

Full -o md output for every command: sample-output.md.

Tips

• Start with `overview` — one call returns a compact summary (metadata, latest + recent versions, license types, vulnerabilities). Reach for doc/examples/module readme/licenses (LARGE) only when the full text is needed.
• Always pass `-o md` so results render as Markdown (tables, or raw doc/README) in the chat. Other formats exist (table default, json, raw) but prefer md here.
• <path> is a full import path, e.g. github.com/samber/lo — pass it as the positional argument.
• --version pins a specific module version (v1.5.0, latest, master, main); --module disambiguates which module a package belongs to.
• --filter narrows list results server-side with a Go boolean expression — see Filter syntax.
• --goos/--goarch set the documentation/symbols build context (e.g. linux/amd64).
• Prefer symbol doc/symbol examples over the package-wide package doc/package examples when you only need one symbol — far fewer tokens.
• Parallelize independent lookups — every command is a self-contained, read-only HTTP query, so calls never depend on each other. When a task needs docs, examples, versions, or vulns for several symbols, packages, or modules, issue all the calls at once (multiple godig invocations in a single turn) rather than one after another — wall-clock drops from sum-of-latencies to slowest-single-call. For a large fan-out (documenting many symbols, comparing many candidate libraries, auditing CVEs across a dependency set), dispatch parallel sub-agents (up to 5) via the Agent tool, each running its own godig calls and returning a compact summary, so the raw LARGE output never lands in the main context.
• Listing commands auto-paginate (return all results); use --limit to cap.

Filter syntax

--filter (on search, versions, major-versions, packages, imported-by, symbols) takes a Go boolean expression evaluated server-side, once per result item. It is not a regex — wrap the whole expression in single quotes for the shell.

• Identifiers are the item's fields, which differ per command — a field valid for one list is rejected by another (e.g. search exposes packagePath, not path). An unknown field fails with undefined identifier: <name> (HTTP 400), which names the offending field. Fields use the item's lowercase JSON key; the exception is enum-like values such as kind, which are capitalized (Function, not func).
• Operators: == != < <= > >=, boolean && || !, parentheses for grouping.
• String functions: contains(s, sub), hasPrefix(s, pre), hasSuffix(s, suf).
• Literals: double-quoted strings ("Function"), true/false, numbers.

Filterable fields per command (string unless noted):

godig symbols github.com/samber/lo --filter 'kind=="Function"' -o md
godig symbols github.com/samber/lo --filter 'kind=="Function" && hasPrefix(name,"Map")' -o md
godig versions github.com/samber/lo --filter 'hasPrefix(version,"v1.5")' -o md
godig versions github.com/samber/lo --filter 'deprecated==false && retracted==false' -o md
godig search "result option" --filter 'hasPrefix(packagePath,"github.com/samber/")' -o md

Examples

Always request Markdown output (-o md):

# Overview — start here (compact, one call)
godig overview github.com/samber/ro -o md

# Search
godig search "result option monad" --limit 5 -o md

# Package facets
godig package info github.com/samber/ro -o md
godig package imports github.com/samber/ro -o md
godig package doc github.com/samber/ro --format md -o md
godig package examples github.com/samber/ro --symbol Map -o md
godig package licenses github.com/samber/ro -o md

# Single symbol (token-efficient vs package-wide doc/examples)
godig symbol doc github.com/samber/lo Map -o md
godig symbol examples github.com/samber/oops OopsError.Error -o md

# Module facets
godig module info github.com/samber/ro -o md
godig module readme github.com/samber/ro -o raw
godig dependencies github.com/samber/ro -o md

# Lists (auto-paginated; --limit to cap)
godig versions github.com/samber/ro -o md
godig major-versions github.com/samber/lo -o md
godig packages github.com/samber/ro -o md
godig imported-by github.com/samber/ro --limit 20 -o md
godig symbols github.com/samber/ro --filter 'kind=="Function"' -o md

# Pin a version / set the build context
godig versions github.com/samber/ro --filter 'hasPrefix(version,"v0.3")' -o md
godig package doc github.com/samber/lo --version v1.50.0 -o md
godig symbols github.com/samber/ro --goos linux --goarch amd64 -o md

# Vulnerabilities
godig vulns github.com/samber/ro -o md

---

This skill is not exhaustive. godig --help and each sub-command's --help list current flags and output formats; the data mirrors what pkg.go.dev exposes.

If you encounter a bug or unexpected behavior in godig, open an issue at <https://github.com/samber/godig/issues>.

godig sample output

Representative -o md output for each command, captured against godig v0.2.0. Empty cells are shown as —. Field sets mirror the underlying APIs — pkg.go.dev for most commands, the Go vulnerability database (vuln.go.dev, OSV) for vulns — and may grow over time.

overview

godig overview github.com/samber/ro -o md

search

godig search ro --limit 3 -o md

package info

godig package info github.com/samber/ro -o md

package imports

godig package imports github.com/samber/ro -o md — a plain list (no --limit):

- context
- errors
- fmt
- ...

versions

godig versions github.com/samber/ro --limit 3 -o md

major-versions

godig major-versions github.com/samber/lo -o md

imported-by

godig imported-by github.com/samber/ro --limit 3 -o md

vulns

godig vulns github.com/dgrijalva/jwt-go -o md

Since v0.2.0 vulns reads the Go vulnerability database (vuln.go.dev, OSV) directly, so summary and per-range fix versions are populated (they were empty when sourced from pkg.go.dev). fixedVersion is gone — fixed/introduced versions now live in ranges; new aliases, packages and references fields are also returned.

vulns returns an empty list when a module has no known vulnerabilities. --filter and --module no longer apply to vulns; only --version and --limit do.

dependencies

godig dependencies github.com/samber/ro -o md — one section per go.mod block (requires, replaces, excludes, go directive):

## requires

| path                       | version | indirect |
| -------------------------- | ------- | -------- |
| github.com/samber/lo       | v1.52.0 | —        |
| github.com/davecgh/go-spew | v1.1.1  | true     |

module info

godig module info github.com/samber/ro -o md

packages

godig packages github.com/samber/ro --limit 4 -o md

symbols

godig symbols github.com/samber/ro --limit 4 -o md

symbol doc

godig symbol doc github.com/samber/lo Map -o md — token-efficient vs package doc:

Raw / large output

package doc, package examples, symbol examples and module readme return raw Markdown (use -o md or -o raw), e.g.:

# package ro

## Constants

...

package licenses and module licenses return the full license text.