AI

MCP Tool Description Checker

Paste your MCP tool description and get a rules-based quality check. Scores clarity, specificity, and agent usability — flags vague words, missing action verbs, and weak patterns — and suggests improvements. No AI involved.

Tool Description

Aim for 50–200 characters0 chars

What makes a good MCP tool description?

❌ Weak descriptions

✗

"Processes data."

✗

"A useful tool for managing things."

✗

"This tool handles user requests."

✗

"Does stuff with the database."

✅ Strong descriptions

✓

"Returns a list of open support tickets filtered by priority."

✓

"Searches internal documents by query. Returns up to 10 results with title and URL."

✓

"Creates a new calendar event. Use when the user wants to schedule a meeting."

✓

"Validates an API key. Returns { valid: true } or an error message."

Description template

[Action verb] [what it does]. [What it returns].
Use when [scenario]. [Any constraints or side effects].

Examples:
"Searches the product catalog by keyword. Returns a list of
matching products with name, price, and stock status.
Use when the user asks about products or wants to find items."

"Creates a new user account with the given email and role.
Returns the new user ID. Requires admin permissions.
Do not call if the user already exists."

Privacy: This tool runs entirely in your browser. Nothing is uploaded or stored.

Frequently Asked Questions

Why does the tool description matter so much in MCP?
The description is the primary signal the AI model uses to decide whether to call a tool. A vague or short description causes the model to skip the tool when it should be used, or call it when it should not. Good descriptions explain what the tool does, what it returns, and when to call it.
What does the clarity score measure?
Clarity measures how easy the description is to understand — whether it uses an action verb, avoids vague words, and has enough detail. A high clarity score means the model can quickly grasp what the tool does.
What does the specificity score measure?
Specificity measures how precisely the description describes the tool's inputs, outputs, and constraints. Mentioning parameter names, return values, or conditions (e.g. "only works for users with admin role") increases specificity.
What does the agent usability score measure?
Agent usability measures how actionable the description is for an AI agent. Does it say when to call the tool? Does it avoid vague verbs? A high score means the model is more likely to call the tool at the right moment.
Is this scoring AI-generated?
No. All checks and scoring are deterministic rules — keyword detection, length checks, and pattern matching. No AI model or API is involved. The same description always produces the same score.
Is my description uploaded anywhere?
No. Everything runs in your browser. Your tool description and schema are never sent to any server.

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