mcp-tool-definition

mcp-tool-definition is a cursor rule for Cursor from netanelavr/trading-mcp. It costs 58 tokens per session (541 once invoked), scanned A, original, MIT.

A writing rule for defining tools in an MCP server, a system that lets an agent call external tools.

In plain words
What is it for?
Use it when adding or editing MCP tool titles and descriptions, especially to document use cases and expected results.
Why use it?
It makes each tool's purpose, suitable use, behavior, and output clear enough for agents to find and choose it correctly.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Use it when adding or editing MCP tool titles and descriptions, especially to document use cases and expected results.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/netanelavr/trading-mcp/mcp-tool-definition
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/netanelavr/trading-mcp

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for mcp-tool-definition

README.md
[![agentmods](https://agentmods.dev/badge/rules/netanelavr/trading-mcp/mcp-tool-definition/github.svg)](https://agentmods.dev/rules/netanelavr/trading-mcp/mcp-tool-definition)
Your own site
<a href="https://agentmods.dev/rules/netanelavr/trading-mcp/mcp-tool-definition"><img src="https://agentmods.dev/badge/rules/netanelavr/trading-mcp/mcp-tool-definition/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for mcp-tool-definition

Your own site · 80×15
<a href="https://agentmods.dev/rules/netanelavr/trading-mcp/mcp-tool-definition"><img src="https://agentmods.dev/badge/rules/netanelavr/trading-mcp/mcp-tool-definition.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 541 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00058 $0.00541
Opus 5 $0.00029 $0.00270
Sonnet 5 $0.00012 $0.00108
Haiku 4.5 $0.00006 $0.00054

Measured 9d ago against content hash f1e99473e5a5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

mcp-tool-definition scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/mcp-tool-definition.mdc · 55 lines

How it starts

The opening of the file, as written. The whole thing — 55 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP Tool Definitions

When adding or editing an MCP Server's tool, follow this structure to make it clear when and how the tool should be used:

Tool Title

The title should clearly indicate what the tool accomplishes or produces. Focus on the outcome or capability - what will it do for the user? Examples:

  • "Screen Stocks by Technical Patterns" (not "Stock Screening Tool")
  • "Analyze Insider Trading Activity" (not "Insider Data Tool")
  • "Calculate Financial Health Score" (not "Health Score Generator")

Tool Description

The description should cover four key aspects:

  1. What is it? - Brief explanation of the tool's purpose
  2. What does it do? - Functionality explanation
  3. When to use it? - Clear use cases and scenarios
  4. What it returns/effects? - Expected outputs or side effects

Descriptions should be comprehensive enough for an AI agent to understand when this tool is the appropriate choice over others.

Example format:

"This tool [what it is] that [what it does]. Use this when [when to use it, specific scenarios]. 
The tool will [what it returns/effects]. [Additional context or limitations if relevant]."

Trading-Specific Examples:

Good:

"Comprehensive stock screening using Finviz filters that supports technical patterns, fundamental criteria, and multi-parameter filtering. Use this when you need to find stocks matching specific investment criteria like channel down patterns, profitable companies, or large-cap stocks. The tool returns a ranked list of stocks with key metrics including market cap, P/E ratios, and current prices. Supports complex filter combinations for advanced screening strategies."

Poor:

"Advanced stock filter for custom screening with multiple filter combinations."

Good:

"Financial health analysis tool that calculates a comprehensive score based on profitability, liquidity, leverage, efficiency, and growth metrics. Use this when evaluating the overall financial strength of a company for investment decisions or risk assessment. Returns a weighted health score (0-100) with detailed breakdowns of each category and actionable insights. Allows custom weighting of different financial factors."

Read the full file on GitHub · 55 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 55 lines · 58 tokens per session scan A f1e99473e5a5

Subscribe to this mod's changes

mcp-tool-definition is a cursor rule published in the GitHub repository netanelavr/trading-mcp (75 stars, last pushed 1y ago), licensed MIT. It adds 58 tokens to every session and 541 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.