improve: enhance tool descriptions for better LLM agent tool selection

[spidershield-contrib]

What

Rewrote all 8 MCP tool descriptions using an action-verb-first format designed for LLM agent planning.

Why

MCP tool descriptions serve as planning hints — LLMs use them to select which tool to call and in what order. The current single-sentence descriptions (e.g., "Update documents in a MongoDB collection") don't help LLMs distinguish between query vs. aggregate, or update vs. insert, leading to tool selection errors.

Format applied

Each description now includes:

• Action verb lead — what the tool does
• Use when — concrete scenarios for this tool
• Do not use when — disambiguation with sibling tools (e.g., "use aggregate instead")
• Accepts — key parameters with types
• Raises an error if — failure conditions

Example: query (before → after)

Before:

Execute a MongoDB query with optional execution plan analysis

After:

Execute a MongoDB find query to retrieve documents from a collection, with optional execution plan analysis.

Use when the user wants to read, search, or filter documents in a specific collection.
Do not use when you need to perform multi-stage data transformations (use aggregate instead) or when you want to modify data (use update or insert instead).
Accepts 'collection' (required), 'filter' (optional query object), 'projection' (optional field selection), 'limit' (optional, default 10), and 'explain' (optional, for query plan analysis).
Raises an error if the collection does not exist or the filter syntax is invalid.

Scope

• 1 file changed (src/schemas/tools.ts)
• 8 tool descriptions rewritten
• Pure string replacement — no logic, schema, or API changes
• Build verified (npm run build ✓), lint verified (npm run lint ✓)

🤖 Descriptions improved with spidershield — open-source MCP security & quality scanner.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the clarity and utility of MongoDB tool descriptions for LLM agents. By adopting a structured, action-verb-first format with detailed usage guidelines, the changes aim to minimize tool selection errors and improve the overall planning capabilities of AI systems interacting with MongoDB.

Highlights

• Enhanced LLM Agent Tool Descriptions: Rewrote all 8 MongoDB tool descriptions to an "action-verb-first" format, specifically designed to improve LLM agent planning and tool selection accuracy.
• Detailed Description Structure: Each tool description now includes explicit sections for "Use when" (concrete scenarios), "Do not use when" (disambiguation), "Accepts" (key parameters), and "Raises an error if" (failure conditions).

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Changelog

• src/schemas/tools.ts
  • Rewrote descriptions for 8 MongoDB tools (query, aggregate, update, serverInfo, insert, createIndex, count, listCollections) to improve clarity for LLM agents.

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[gemini-code-assist]

Code Review

This pull request significantly improves the tool descriptions to aid LLM agent planning. The new detailed format is a great enhancement. My review focuses on ensuring the descriptions are complete and consistent. I've found that several tool descriptions are missing some of their available parameters, which could limit the LLM's ability to use them effectively. I've also suggested using template literals for multi-line strings to improve code readability and maintainability.