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

Annotations already declare readOnlyHint=true, so the safety profile is covered; the description adds no further behavioral detail. It doesn't describe what is returned beyond naming three fields, what happens if the optional key is omitted (own account vs. anonymous?), or any auth/rate-limit behavior.

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, front-loaded with the return contents, no filler. The trigger sentence partly restates the field list ('balance, credits, usage') but still earns its place as routing guidance.

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, so naming the three returned items is reasonably sufficient for a simple read tool with readOnlyHint annotations. The main gap is the unaddressed role of the optional key and the unresolved overlap with 'checkBalance'.

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 is documented as an optional PromptGPT Sync Key with an example format. The description never mentions the key parameter at all, so it adds zero meaning about what supplying vs. omitting it changes — notable since the tool is only meaningful if the key resolves an 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 set: 'Returns current credit balance, usage status, and account information.' An agent can tell what it fetches. However, it never differentiates itself from the sibling tool 'checkBalance', which sounds like an overlapping read of the same resource — a meaningful ambiguity left unresolved.

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?

Provides explicit trigger conditions: 'Trigger this whenever the user mentions balance, credits, usage, or asks to check credits' — clear positive context for invocation. It offers no exclusions or alternatives, notably failing to say when 'checkBalance' or 'syncAccount' should be preferred instead.

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