Guidance for working with Protocol Buffers, a language-neutral format for defining structured data and service interfaces. It covers .proto files, buf configuration, gRPC or Connect services, validation, and schema changes.

Use it when creating or editing Protocol Buffer schemas, configuring buf, designing gRPC or Connect APIs, adding validation rules, or fixing buf lint and compatibility errors.

It helps keep data schemas compatible as systems evolve and catches formatting, lint, validation, and breaking-change problems. It also provides a consistent workflow for designing and checking service definitions.

protobuf — Skill for Claude Code by bufbuild/claude-plugins

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add bufbuild/claude-plugins --skill protobuf

Clone the repo

git clone --depth 1 https://github.com/bufbuild/claude-plugins

Made for: Claude Code.

Or install protobuf, the plugin that ships this one along with the rest of its 1 skill.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/bufbuild/claude-plugins/protobuf/github.svg)](https://agentmods.dev/skills/bufbuild/claude-plugins/protobuf)

Your own site

<a href="https://agentmods.dev/skills/bufbuild/claude-plugins/protobuf"><img src="https://agentmods.dev/badge/skills/bufbuild/claude-plugins/protobuf/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/bufbuild/claude-plugins/protobuf"><img src="https://agentmods.dev/badge/skills/bufbuild/claude-plugins/protobuf.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,166 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

Socket pass 15 Sept 2026
Snyk pass 15 Sept 2026
NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00054	$0.01166
Opus 5.5	$0.00022	$0.00466
Sonnet 5.5	$0.00011	$0.00233
Haiku 4.5	$0.00005	$0.00117

Measured 2mo ago against content hash 8b09f409f34a, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

protobuf scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

protobuf — 100% identical, 0 lines differ

plugins/protobuf/skills/protobuf/SKILL.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Protocol Buffers

When You Need This Skill

Creating or editing .proto files
Setting up buf.yaml or buf.gen.yaml
Designing gRPC or Connect services
Adding protovalidate constraints
Troubleshooting buf lint or breaking change errors

Core Workflow

1. Match Project Style

Before writing proto code, review existing .proto files in the project. Match conventions for naming, field ordering, structural patterns, validation, and documentation style. If none exists, ask the user what style should be used or an existing library to emulate.

2. Write Proto Code

Apply universal best practices from best_practices.md
Add protovalidate constraints to every field—this is not optional for production APIs
For service templates, see assets/

3. Verify Changes

Always run after making changes:

buf format -w && buf lint

Check for a Makefile first—many projects use make lint or make format.

Fix all errors before considering the change complete.

Quick Reference

Task	Reference
Field types, enums, oneofs, maps	quick_reference.md
Schema evolution, breaking changes	best_practices.md
Validation constraints	protovalidate.md
Complete service examples	examples.md, assets/
buf CLI, buf.yaml, buf.gen.yaml	buf_toolchain.md
Migrating from protoc	migration.md
Lint errors, common issues	troubleshooting.md
Proto API review checklist	review_checklist.md

Project Setup

New Project

Create directory structure:

proto/
├── buf.yaml
├── buf.gen.yaml
└── company/
    └── domain/
        └── v1/
            └── service.proto

Read the full file on GitHub · 142 lines

Files

What ships with it

20 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 142 lines · 54 tokens per session scan A 8b09f409f34a

Subscribe to this mod's changes

protobuf is a skill published in the GitHub repository bufbuild/claude-plugins (20 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 54 tokens to every session and 1,166 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs

protobuf next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
protobufbufbuild/claude-plugins	Skill	20	1mo ago	Apache-2.0	A	54	Claude Code
mem0-oss-to-platformmem0ai/mem0	Skill	68k	2d ago	Apache-2.0	A	217	Claude Code, Codex
azure-mgmt-botservice-dotnetmicrosoft/skills	Skill	3.2k	yesterday	MIT	A	78	Claude Code
fastapi-router-pymicrosoft/skills	Skill	3.2k	yesterday	MIT	A	46	Claude Code
dev-runtimelangwatch/langwatch	Skill	5.0k	yesterday	Apache-2.0	A	172	Claude Code
api-designericrisco/rsc-harness	Skill	503	2d ago	MIT	A	105	Claude Code, Codex
migrate-segw-to-raparc-mcp/arc-1	Skill	252	yesterday	MIT	A	106	Claude Code