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

With no annotations provided, the description carries the full behavioral burden. It clearly signals a read-only operation ('Return'), states that no auth is required, and establishes the intended call ordering. It does not disclose output shape, but for a simple query tool that is acceptable.

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?

Two short sentences with no filler. The core action is front-loaded, followed by targeted usage guidance and an auth note. Every sentence earns its place.

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 zero-parameter, no-output-schema tool with low complexity. The description fully covers what the tool does, when to use it, and necessary preconditions. Nothing essential is missing for an agent to select and 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 input schema is empty, so the baseline is 4. The description adds practical context by explaining that this tool informs the amount parameter for topup_create, even though no parameters exist on this tool itself.

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 ('Return') and a concrete resource ('bonus credit tiers applied to top-ups'). It also distinguishes itself from the sibling topup_create by framing the query as a precursor to that write operation.

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?

Explicit guidance is given: use this BEFORE topup_create to choose an amount that maximises free credit. This tells the agent exactly when to invoke this tool relative to an alternative, and 'No auth required' removes a potential prerequisite concern.

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