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

readOnlyHint=true already tells the agent this is a safe read, so the description only needs to add context. It does add the return content (balance, account status, recharge options), but it never says what happens when the optional key is omitted or whether the call is authenticated per-user.

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 sentences with no filler: what it returns first, then when to call it. Nothing redundant or buried.

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?

There is no output schema, and the description compensates by naming what comes back (balance, status, recharge options). The only remaining gap is behavior when the optional key is absent, which matters for a balance lookup.

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% and the single parameter 'key' is fully documented in the schema, so the baseline is 3. The description adds nothing about the key's role — notably whether it is needed to resolve the right account.

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?

States a specific verb and resource ('Checks the remaining PromptGPT credit balance') plus the extra payload (account status, recharge options). It is clear on its own, but it does not distinguish itself from the sibling getAccountUsage, which the 'usage' wording arguably overlaps.

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?

Gives explicit trigger phrases: 'whenever the user asks to check balance, remaining credits, usage, or asks how many credits they have left.' That is clear invocation context, but it offers no exclusion telling the agent when getAccountUsage is the better call instead.

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