fill in the README to not be boilerplate (#19)

Author: tdyas

README.md

@@ -1,27 +1,36 @@
-# Shoal Software Pants Model Context Plugin
+# Pantsbuild Model Context Protocol Plugin
 
-Provides a Model Contect Protocol ("MCP") for a Pants repository for LLM agents to make use of.
+## Overview
+
+This project is an **experimental** plugin to the [Pantsbuild](https://pantsbuild.org/) build orchestration tool to expose a Model Contect Protocol ("MCP") server for LLM coding agents to interact with.
 
 ## Installation
 
-TBD
+From PyPI:
 
-## Usage
+1. In the relevant Pants project, edit `pants.toml` to set the `[GLOBAL].plugins` option to include `shoalsoft-pants-mcp-plugin==VERSION` (replacing `VERSION` with the applicable version) and the `[GLOBAL].backend_packages` option to include `shoalsoft.pants_mcp_plugin`.
 
-TBD
+2. Confogure your LLM coding agent to invoke `pants shoalsoft-mcp --run-stdio-server` in the repository as follows:
 
-## Configuration
+  - [Claude Code setup](https://docs.claude.com/en/docs/claude-code/mcp#option-1%3A-add-a-local-stdio-server)
+  - [ChatGPT Codex setup](https://github.com/openai/codex/blob/main/docs/advanced.md#model-context-protocol-mcp)
 
-TBD
+## Usage
+
+If the MCP server is started correctly by your LLM coding agent, then the agent should take advantage of the exposed MCP tools, which include a tool for each Pants goals.
 
 ## Development
 
-TBD
+### Workflow
+
+- Run formating and type checks (mypy): `pants fmt lint check ::`
+
+- Run tests: `pants test ::`
 
 ### Building
 
 TBD
 
 ## License
 
-This is commercial software and requires prior permission to use.
+This is currently commercial software and requires prior permission to use. See the [LICENSE](./LICENSE) file in this repository for specific details.