mcp-tool-design SKILL.md skillA
mcp-tool-design from sigistry/marketplace is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add sigistry/marketplace/mcp-tool-design@git:20260826.571bc2fPins git:20260826.571bc2f in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- sigistry/marketplace
- Path
plugins/mcp-server-smith/skills/mcp-tool-design/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260826.571bc2f, committed Aug 26, 2026
- First version recorded
- Aug 2, 2026
- Size
- 4,848 bytes
- Repository stars
- 3
- License
- MIT
This skill should be used when the user mentions "MCP tool", "tool design", "tool schema", "inputSchema", "tool annotations", "readOnlyHint", "destructiveHint", "tool description", "resources vs tools", "MCP prompts", or designing the tools/resources/prompts an MCP server exposes to an agent. It provides the design rules for few, powerful, well-schematized tools with accurate annotations and safe errors.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# MCP Tool Design ## Purpose An MCP server's tools are the API the model reasons over, its quality decides whether the agent uses the server well or thrashes. The failure mode is not usually a bug; it is **too many thin, ambiguous tools with loose schemas**, which burn context, invite wrong calls, and hide destructive actions behind innocent names. This skill is the design discipline: few powerful tools, complete schemas, honest annotations, safe errors, bounded output. ## Tools vs resources vs prompts | Primitive | For | Example | |---|---|---| | **Tool** | an **action** the model invokes (may have side effects) | `create_issue`, `run_query`, `search_docs` | | **Resource** | **readable content** addressed by URI, app-controlled | `file://…`, `db://schema`, a document the host attaches | | **Prompt** | a **user-initiated** templated workflow | a `/summarize-pr` slash command | Do not model a read as a destructive tool, or a user workflow as an always-on tool. Picking the right primitive removes whole classes of misuse. ## Few, powerful tools …
Read the whole file at its exact version.
How to install
mdr add sigistry/marketplace/mcp-tool-design@sha256:9c5f44e50d6d6cb7The line at the top of this page pins the label git:20260826.571bc2f, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_qlld6hiozh6uatye)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between Aug 2, 2026 and Aug 26, 2026, about one every 23 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260826.571bc2f latest | 2026-08-26 | 571bc2f | 4,848 B | A | view · diff |
| git:20260802.9f9bd44 | 2026-08-02 | 9f9bd44 | 4,848 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (4848 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
sigistry/marketplace · 3 stars · license MIT · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_qlld6hiozh6uatye GET https://markdownregistry.com/api/v1/resolve?ref=sigistry/marketplace/mcp-tool-design GET https://markdownregistry.com/api/v1/blob/9c5f44e50d6d6cb7e9e87d33f8b8ed6381f105025e2bb899c6a645d0c55cf5ba
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.