Agent: Build a Custom Agent Mode in Cursor for Managing Notes

Creating a simple AI agent in Cursor is straightforward, but making it perform a complex, multi-step task reliably requires more than just a basic prompt. Agents often fail due to missing permissions, a lack of real-world context (like the current date), or an incorrect understanding of the required sequence of actions.

This lesson demonstrates the practical, iterative process of building and refining a sophisticated custom agent from the ground up. You will learn how to meticulously configure the agent's tool permissions, craft detailed step-by-step instructions to guide its behavior, and troubleshoot common failure points.

The result is a powerful, one-click automation that can process a daily note, extract actionable items, and create new issues in a separate project context. This hands-on example showcases how to build robust, personalized AI workflows that go far beyond simple chat commands.

The Process of Refining an Agent

This lesson walks through the real-world process of programming an AI agent, which involves:

• Initial Setup: Creating a new custom agent, assigning it a name ("Create Issues"), and setting a convenient keybinding (Cmd/Ctrl + M).
• Permission Scoping: Starting with a minimal set of tool permissions (e.g., only "Run Commands" and a specific "MCP Server") to ensure security and predictable behavior.
• Detailed Prompting: Providing a comprehensive, multi-step set of custom instructions that act as the agent's core logic or "rule."
• Testing and Observation: Running the agent and carefully observing its output and failure points.
• Iterative Refinement:
  • Adding necessary permissions (like read_file and search_files) only when the agent reports it cannot perform a required action.
  • Enhancing the custom instructions to be more explicit, such as telling the agent how to get the current date with a specific terminal command.
  • Adjusting the order of operations in the instructions to ensure a logical workflow (e.g., reading a local file before switching to a different project context).
• Finalization: Continuing to test and refine until the agent performs the entire desired workflow flawlessly and efficiently with a single command.

Prompts

A prompt to start the demonstration:

Let's make the hero text larger and move it down a little bit.

The simple trigger word used to activate the fully programmed agent:

go

A prompt to give the agent date-awareness:

run a terminal command to determine today's date

Another prompt to help the agent find the correct file:

find the note matching today's date in the following format.

Commands

The terminal command the agent is instructed to use to find the current date:

date +%Y-%m-%d

Code Snippets

The final, refined custom instructions pasted into the agent's configuration. This multi-step prompt guides the agent through the entire workflow, including error handling and context switching.

# Rule: create-issues-from-today

## Description
This rule describes the process for extracting content from a daily note and creating categorized issues (features, fixes, etc.) in a separate memory project.

## Steps (with MCP Tools)
0. Read the content of ./notes/YYYY-MM-DD.md using the read_file tool.
1. **Switch to the 'issues' memory project**
   - Tool: `mcp_basic-memory_switch_project`
   - Usage: Switch to the `issues` project to access its file structure and create new notes.
2. **Extract Actionable Items from Note**
   - Process the content of the daily note provided.
   - For each actionable item (e.g., a bug, a feature request), create a new note in the appropriate folder (`fix/`, `feature/`, etc.) within the `issues` memory project.
   - Tool: `mcp_basic-memory_write_note` (to add references/links in the note content)
   - Usage: If needed, add references back to the original daily note for traceability.
3. **Switch back to the "script-generator" project**
   - Tool: `mcp_basic-memory_switch_project`
   - Usage: Switch back to the "script-generator" project to continue working on the script.

## Example
- A bug described in the daily note becomes a file in `fix/`.
- A performance concern becomes a file in `perf/`.

This process ensures daily notes are systematically converted into actionable, categorized issues for tracking and follow-up.