tool-creation SKILL.md skillA
tool-creation from tylerjrbuell/reactive-agents-ts is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add tylerjrbuell/reactive-agents-ts/tool-creation@v2.0Pins v2.0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- tylerjrbuell/reactive-agents-ts
- Path
apps/docs/skills/tool-creation/SKILL.md- Versions recorded
- 3
- Latest version
- v2.0, committed Jul 21, 2026
- First version recorded
- Apr 10, 2026
- Size
- 5,565 bytes
- Repository stars
- 31
- License
- MIT
Create custom tools with defineTool() or tool(), register them with the agent, and configure required-tools gates and per-tool call budgets.
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
# Tool Creation
## Agent objective
Produce a `ToolDefinition` object + handler, registered with the builder via `.withTools({ tools: [...] })`. Every field in the definition must be present and typed correctly.
## When to load this skill
- Adding a custom tool (API call, database query, file operation, etc.)
- Restricting which built-in tools an agent can use
- Forcing the agent to call a specific tool before completing
- Setting per-tool approval requirements or risk levels
## Implementation baseline
```ts
import { ReactiveAgents } from "@reactive-agents/runtime";
import { tool } from "@reactive-agents/tools"; // simple factory — no Effect knowledge needed
const lookupUser = tool("lookup-user", "Look up a user record by ID", async (args) => {
const { userId } = args as { userId: string };
const user = await db.findUser(userId);
return { id: user.id, name: user.name, email: user.email };
});
const agent = await ReactiveAgents.create()
.withProvider("anthropic")
.withReasoning({ defaultStrategy: "adaptive" })
.withTools({
tools: [lookupUser],
allowedTools: ["lookup-user", "checkpoint"], // restrict to only these
})
…Read the whole file at its exact version.
How to install
mdr add tylerjrbuell/reactive-agents-ts/tool-creation@sha256:38c578d3bd6ddd24The line at the top of this page pins the label v2.0, 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_exaxwlz3mc33bk2a)
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Versions
The registry has recorded 3 versions of this file, between Apr 10, 2026 and Jul 21, 2026, about one every 51 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| v2.0 latest | 2026-07-21 | 848f5ae | 5,565 B | A | view · diff |
| v2.0 | 2026-04-10 | a95c860 | 5,582 B | A | view · diff |
| v2.0 | 2026-04-10 | edbdd5f | 5,448 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 (5565 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
tylerjrbuell/reactive-agents-ts · 31 stars · license MIT · pushed 2026-11-07 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_exaxwlz3mc33bk2a GET https://markdownregistry.com/api/v1/resolve?ref=tylerjrbuell/reactive-agents-ts/tool-creation GET https://markdownregistry.com/api/v1/blob/38c578d3bd6ddd24fcc242d11f8bfe2b3d3b4e975d48bd30141bd3b2dab7ad91
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.