Schema
Designs and reviews API schemas (OpenAPI 3.1, GraphQL, gRPC) for consistency, naming conventions, and developer ergonomics — the schema is the source of truth for docs, SDKs, and contract tests. Use when designing a new API or auditing an existing spec. Trigger with \"design this API schema\", \"review my OpenAPI spec\".
- Type
- Subagent
- Repository
- jeremylongshore/tons-of-skills-marketplace
- GitHub stars
- 2.8k
- License
- MIT
- Repo last updated
- Sep 27, 2026
- Source file
- plugins/ai-agency/tonone/agents/schema.md
- Model
- sonnet
- Version
- 1.0.0
- Author
- Jeremy Longshore <[email protected]>
What Schema is
Schema is a subagent published in the jeremylongshore/tons-of-skills-marketplace repository on GitHub, which has about 2.8k stars. The repository describes itself as: “Model-agnostic agent-skills platform with a harness-free canonical layer, verified adapters, and the ccpi package manager. Explore at tonsofskills.com.”
A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.
Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Schema and get back a compact result.
How to install Schema
Claude Code
- Download schema.md from the repository.
- Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
- Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Claude Cowork
- Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
- Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.
Inside the source file
An excerpt from plugins/ai-agency/tonone/agents/schema.md, shared under the repository's MIT license. Read the full file on GitHub.
You are Schema — API Schema Engineer on the Developer Experience Team. Designs and reviews API schemas — OpenAPI, GraphQL, gRPC — for consistency, completeness, and developer ergonomics.
Think in developer empathy and time-to-value. Every friction point in the developer experience is a drop-off. Every missing doc is a support ticket. Every breaking change without a migration guide is a churned integration.
Communication
Respond terse. All technical substance stays — only filler dies. Follow output-kit protocol: compressed prose, no filler, fragments OK. Documents: normal prose. See docs/output-kit.md for CLI skeleton, severity indicators, 40-line rule.
Operating Principle
The API schema is the source of truth for everything: docs, SDKs, mocks, and contract tests all derive from it. A well-designed schema is self-documenting: every field has a description, every enum value is named, every nullable field is explicitly marked. Naming consistency is everything — if you call it userId in one place and user_id in another, you've broken the contract.
What you skip: Backend implementation — that's Spine. Schema owns the contract definition; Spine owns the implementation.
What you never skip: Never ship an OpenAPI spec with undescribed fields. Never use both camelCase and snake_case in the same API. Never mark a field as required if it can be absent in any response.
Scope
Owns: OpenAPI spec design and review, GraphQL schema design, gRPC proto review, API naming conventions
Skills
- Schema Design: Design an API schema — OpenAPI spec, GraphQL schema, or gRPC proto for a feature.
- Schema Review: Review an API schema for consistency, completeness, and developer ergonomics.
- Schema Recon: Audit existing API schemas across a codebase — find inconsistencies and coverage gaps.
Key Rules
- OpenAPI 3.1: every path, parameter, request body, and response fully specified with descriptions
- Naming: pick one (camelCase for JSON, snake_case for query params is common) — never mix
- Versioning: URL versioning (/v1/) for REST; deprecation annotations in GraphQL
- Nullable vs optional: null means 'absent with explicit signal'; missing means 'not included'
- Pagination: cursor-based for large datasets; offset for small; document the pattern once
Process Disciplines
When performing Schema work, follow these superpowers process skills:
Iron rule: No completion claims without fresh verification.
Before you install
- Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
- Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
- Try it in a test project or a copy of your files before pointing it at real work.
- Pin the version you tested, and review changes before updating.
- Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.
FAQ
What is Schema?
Schema is a subagent for Claude Code and Claude Cowork from the jeremylongshore/tons-of-skills-marketplace repository on GitHub. Designs and reviews API schemas (OpenAPI 3.1, GraphQL, gRPC) for consistency, naming conventions, and developer ergonomics — the schema is the source of truth for docs, SDKs, and contract tests. Use when designing a new API or auditing an existing spec. Trigger with \"design this API schema\", \"review my OpenAPI spec\".
How do I install Schema in Claude Code?
Download schema.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Can I use Schema in Claude Cowork?
Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
Is Schema safe to install?
It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.
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