---
id: "anthropic-writing-tools-for-agents"
title: "Writing effective tools for AI agents"
creator: "Anthropic"
creator_url: "https://www.anthropic.com/engineering/writing-tools-for-agents"
url: "https://www.anthropic.com/engineering/writing-tools-for-agents"
level: "advanced"
level_max: null
category: "agents"
subcategory: "tool-use-and-mcp"
region: "West"
license: "closed"
license_scope: "linked-resource"
models: ["any"]
source_date: "2025-09-11"
date_added: "2026-10-18"
---

[Agents and harnesses](/agents/index.md)

# Writing effective tools for AI agents

by [Anthropic](https://www.anthropic.com/engineering/writing-tools-for-agents)

[Read the original →](https://www.anthropic.com/engineering/writing-tools-for-agents)

How to design, evaluate and improve the tools an agent calls.

Anthropic discusses shaping tool interfaces and evaluating how agents use them. The emphasis is on testing whether a tool helps accomplish the task rather than merely exposing an API.

Level: [Advanced](/levels/index.md#advanced)
Models: any
Category: [Agents and harnesses](/agents/index.md)
Tags: [tools](/tags/tools/index.md)
Source date: 2025-09-11
Added: 2026-10-18
Last verified: 2026-10-18
Status: ok
Prerequisites: Requires implementation experience or critical reading of technical methods and system trade-offs.
Subcategory: [tool use and mcp](/agents/tool-use-and-mcp/index.md)
Region: West
Original language: en
Access: free
Resource reuse: closed: No general open-reuse grant established from the inspected page. Closed is the conservative index bucket, not a legal finding; the resource is publicly readable. [Facet definitions](/about/index.md#facets)

Summary in our own words. Rights remain with the original creator. [Credit and correction policy](/about/index.md#credit-policy).

[Plain-text Markdown copy](/agents/tool-use-and-mcp/anthropic-writing-tools-for-agents/index.md)