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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe, non-mutating operation. The description adds a list of what is checked (credit balance, rewards, tier) but does not disclose any additional behavioral traits such as return format, network requirements, or limitations. It does not contradict the 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 concise and front-loaded with the key purpose. However, the phrase 'FREE. (FREE)' is redundant and adds no value, making it slightly less polished than a perfectly concise description.

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 simple read-only tool with one parameter and no output schema, the description is sufficiently complete. It tells the user what information can be retrieved. It does not describe return values, but that is not required given the simplicity and lack of output schema. A small gap is the absence of any note about the response format or whether the wallet must be registered.

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 schema provides 100% coverage for the only parameter 'wallet' with a description ('Your EVM wallet address (0x...)'). The tool description does not add any further meaning beyond the schema, so the baseline score of 3 applies.

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's function: 'Check your GCX credit balance, loyalty rewards, and volume tier.' It uses a specific verb ('check') and resource (balance/rewards/tier), and this is the only balance-checking tool among siblings, so it is well-distinguished.

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 the tool should be used when a user wants to see their GCX credit balance, loyalty rewards, or volume tier, but it provides no explicit guidance on when to use it versus alternatives or any prerequisites. There are no competing tools for this purpose, but the usage context is only implied.

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