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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds behavioral context by specifying what information is returned (credit balance, plan, end date) and clarifying the separation from wallet funds. This goes beyond the annotations without contradicting them.

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, front-loaded with the core purpose in the first sentence and usage triggers in the second. Every sentence adds value, including the important distinction from wallet money. No redundancy.

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?

For a zero-parameter read-only tool with output schema and annotations, the description is complete. It covers what, when, and a potential pitfall, while the output schema handles return format details. No significant gaps.

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?

There are zero parameters, so the baseline is 4 per the rubric. The description adds meaning by explaining the tool's output (credits and plan) even though no parameter details are needed. It fully compensates for the lack of parameters.

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 clearly states the tool retrieves the operator's remaining AI credit balance and current subscription plan including end date. It uses a specific verb (get/retrieve) and resource (credits and plan), and distinguishes it from wallet-related tools explicitly.

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?

It provides explicit triggers: 'Call this when they ask how many credits are left, whether they can still run AI effects, or what plan they are on.' It also warns against confusing credits with wallet money, effectively guiding the agent away from sibling tools like get_wallet_transactions.

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