Customize a built-in agent

Connect a web server

Add the fetch MCP server to .graph/config.toml. Its fetch tool joins your catalog as web__fetch:

.graph/config.toml

[mcp.web]
description = "Fetches web pages as markdown"
command = "uvx"
args = ["mcp-server-fetch"]

Create the researcher

.graph/agents/researcher.yaml

version: 1
name: researcher
description: Researches a question on the internet and answers with sources.
model: chat
tools:
- web__fetch
system_prompt: |
  You research questions on the internet. Fetch the pages you need, then
  answer briefly and list the URLs you used.

Copy the chat agent

A file named chat in your project replaces the built-in:

graph agent show chat \
  > .graph/agents/chat.yaml

Add the subagent

Add researcher to subagents, and tell chat when to use it in system_prompt:

.graph/agents/chat.yaml

subagents:
- chat
- researcher
system_prompt: |
  …
  - When a question needs current information from the internet, give it to agent__researcher and cite the sources it returns.

  Current date and time: {{session.date}}
  {{session.user}}

Try it

graph ask "What is the latest stable version of Rust?"

chat hands the question to researcher, which fetches the pages:

→ agent__researcher {"prompt":"What is the latest stable version of the Rust programming language…"}
→ web__fetch {"url":"https://www.rust-lang.org/"}
→ web__fetch {"url":"https://releases.rs/"}
✓ web__fetch 1.9s
✓ web__fetch 2.4s
→ web__fetch {"url":"https://releases.rs/docs/1.99.0/"}
→ web__fetch {"url":"https://blog.rust-lang.org/"}
✓ web__fetch 494.1ms
✓ web__fetch 1.1s
✓ agent__researcher 10.0s
The latest stable version of Rust is **1.99.0**, released on **October 1, 2026**.

Sources: releases.rs, and the official announcement at blog.rust-lang.org/2026/10/01/Rust-1.99.0/

Build a multi-agent network

Connect agents with handoffs and subagents.

Connect an MCP server

Add other servers’ tools to your catalog.

Talk to an agent

Use chat with graph ask and graph chat.

Create an agent in the workbench

Draft the researcher with the agent drafter instead.

Getting started

Agents

Plans

Tools

Packs

Integrating

Reference

Customize a built-in agent

Connect a web server

Create the researcher

Copy the chat agent

Add the subagent

Try it

Build a multi-agent network

Connect an MCP server

Talk to an agent

Create an agent in the workbench

​Connect a web server

​Create the researcher

​Copy the chat agent

​Add the subagent

​Try it

​Related guides

Build a multi-agent network

Connect an MCP server

Talk to an agent

Create an agent in the workbench

Connect a web server

Create the researcher

Copy the chat agent

Add the subagent

Try it

Related guides