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

There are no annotations, so the description carries the burden of behavioral disclosure. It adds useful context about required authorization ('Bearer ck_live_… or X-Clink-Key') and cost ('Free'), but it does not describe the response format, error cases, or explicitly confirm this is a read-only operation beyond the word 'Check.'

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?

One sentence contains the verb, resource, scoping detail, auth mechanism, and cost. There is no filler, and the key facts are front-loaded.

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 balance check with no output schema, the description provides enough to invoke it correctly: what it returns conceptually, which key it applies to, and how to authenticate. It only omits formatting details of the returned balance, which is minor for this simplicity level.

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 and schema coverage is effectively complete, so there is no parameter ambiguity. The description appropriately focuses on the non-schema details that matter for invocation: auth headers and cost.

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 states a specific verb ('Check'), a specific resource ('shop-credits balance'), and the scoping context ('for the key on this connection'). It also names the relevant auth headers, making the operation identifiable and distinct from buy_credits.

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 makes the intended use unambiguous: call this to check the shop-credits balance for the current key. It does not explicitly discuss exclusions or alternatives, but with no other balance-checking sibling and a zero-parameter interface, the context is clear enough.

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