building-agent-tools

building-agent-tools is a skill for Claude Code from nek1987/auto-agent-harness. It costs 46 tokens per session (566 once invoked), scanned A, original, no licence file.

A guide to designing tools that AI agents can call, including MCP tools and agent APIs. MCP is a standard way for AI systems to use external tools.

In plain words
What is it for?
Use it when building, naming, organising, or reviewing tools and APIs intended for AI agents.
Why use it?
It helps avoid interfaces that waste context or make the available actions unclear to an agent.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

Good fit Use it when building, naming, organising, or reviewing tools and APIs intended for AI agents.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nek1987/auto-agent-harness/building-agent-tools
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 nek1987/auto-agent-harness --skill building-agent-tools
Clone the repo
git clone --depth 1 https://github.com/nek1987/auto-agent-harness

Made for: Claude Code.

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.

agentmods badge for building-agent-tools

README.md
[![agentmods](https://agentmods.dev/badge/skills/nek1987/auto-agent-harness/building-agent-tools/github.svg)](https://agentmods.dev/skills/nek1987/auto-agent-harness/building-agent-tools)
Your own site
<a href="https://agentmods.dev/skills/nek1987/auto-agent-harness/building-agent-tools"><img src="https://agentmods.dev/badge/skills/nek1987/auto-agent-harness/building-agent-tools/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.

agentmods 80×15 button for building-agent-tools

Your own site · 80×15
<a href="https://agentmods.dev/skills/nek1987/auto-agent-harness/building-agent-tools"><img src="https://agentmods.dev/badge/skills/nek1987/auto-agent-harness/building-agent-tools.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 566 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.
Origin unknown 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00046 $0.00566
Opus 5 $0.00023 $0.00283
Sonnet 5 $0.00009 $0.00113
Haiku 4.5 $0.00005 $0.00057

Measured 9d ago against content hash e665939f7000, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

building-agent-tools 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 9d 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.

.claude/skills/building-agent-tools/SKILL.md · 81 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

Files

What ships with it

1 file 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.

  1. 9d ago First seen · 81 lines · 46 tokens per session scan A e665939f7000

Subscribe to this mod's changes

building-agent-tools is a skill published in the GitHub repository nek1987/auto-agent-harness (5 stars, last pushed 5mo ago), with no licence file. It adds 46 tokens to every session and 566 once invoked, about $0.0002 per session on Opus 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 2026-08-31.

Related

Other skills, from other repositories

api-debugging

Systematic approach to debugging REST APIs, HTTP errors, authentication issues, and network problems. Use when the user has API errors, status code issues, timeout problems, or needs help troubleshooting HTTP requests.

ownpilot/OwnPilot · 44 tokens

api-design-reviewer

Use when reviewing a PR that adds or changes API endpoints, auditing an existing API for v2 migration, or establishing REST API standards. Triggers on "API review", "REST design review", "breaking change check", "OpenAPI audit", "endpoint review", or "API consistency".

tmj-90/gaffer · 63 tokens

backend-service

Use when a ticket asks for backend business logic that isn't itself an endpoint or a migration — a service/use-case, a domain operation, a background job, or orchestration across repositories. Invoke for "add a service to do X", "implement the use-case", or "extract the business logic out of the handler".

tmj-90/gaffer · 67 tokens

add-api-endpoint

Use when a ticket asks to add or extend an HTTP/API endpoint — a new route, handler, or RPC method — with request validation and a defined response. Invoke for "add a POST /things endpoint", "expose a list API", or "add a field to the X response".

tmj-90/gaffer · 64 tokens

doc-generator

Auto-generate API reference documentation from Python code.

XSpoonAi/spoon-awesome-skill · 13 tokens

claude-api

Use this skill when the user is building against Anthropic APIs or SDKs, including @anthropic-ai/sdk, anthropic, or Agent SDK integrations.

lk19940215/claude-coder · 0 tokens