Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, but the description adds valuable behavioral context beyond those: it states that the tool 'Works without authentication' and 'returns general info', clarifying what the caller can expect without credentials. This is meaningful context not captured in annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences with no waste. The first sentence front-loads the action and resource, the second enumerates the return items and adds the authentication nuance. Every word adds value and it is easy to scan.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This is a simple, zero-argument tool with a rich output schema and strong annotations. The description covers the tool's purpose, the specific data returned, and the important authentication behavior. Nothing critical is missing for an agent to invoke it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, so the description doesn't need to explain parameter behavior. Per the scoring guideline, a 0-parameter tool gets a baseline of 4, and the description effectively covers the tool's return aspects without needing parameter documentation.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Returns') and identifies the exact resource ('usage statistics for your ThinkNEO API key'), then explicitly enumerates the data points shown (calls today, this week, this month, monthly limit, etc.). It clearly distinguishes itself from the many sibling tools by focusing solely on API key usage, which no other tool claims.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies when to use this tool (to check API key usage) but does not explicitly compare it to alternatives like get_budget_status or get_savings_report. The note about working without authentication hints at a differentiator, but there are no explicit exclusions or 'use this instead of X' guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.