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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It never explicitly states that this is a read-only operation, what the tool returns, or whether it has side effects. The phrasing 'Your credit balance and ledger' implies retrieval, but an agent is left to infer the safety profile.

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 short sentences with no wasted words. The core resource is stated first, and the relevant sibling routing follows immediately. It is highly scannable for an agent.

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 tool with zero required parameters, a single optional parameter, and no output schema, the description is nearly complete. It names the resource and points the agent to the correct sibling for a mutating alternative. The main gap is that the return shape and read-only nature are implied rather than stated.

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?

Schema coverage is 100%, so the api_key parameter is already fully described with its prefix and optional Bearer-header fallback. The description adds no parameter-specific meaning beyond the schema. This matches the baseline for well-covered schema 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 identifies the resource precisely: the agent's credit balance and ledger. It doesn't use an explicit verb like 'get' or 'view', but the noun phrase clearly conveys what the tool exposes internally. It also differentiates from the sibling octopus_topup by routing credit-adding behavior away.

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 gives an explicit alternative for a related action: 'To add credits: octopus_topup.' This helps an agent choose between wallet and topup. It doesn't enumerate all non-uses, but for a simple balance tool the relevant exclusions are mostly covered.

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