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

Annotations already fully declare the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description only needs to add context — and it adds none. It does not say whether the response is a single number, a breakdown, or whether it expires, leaving the agent with nothing beyond the structured hints.

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?

A single front-loaded sentence with the usage trigger stated first and no filler. Nothing could be removed without losing the 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?

For a zero-parameter, non-destructive read with full annotation coverage, the description is sufficient to select and call the tool. The only gap is the shape of the returned value, which is a minor omission given no output schema exists.

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 takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a parameterless tool applies. The description correctly avoids inventing inputs.

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 names a specific resource and scope — remaining VecSnap credits — and the trigger phrasing makes the intent unambiguous. It does not explicitly contrast with siblings, but since none of the listed siblings deal with credits, disambiguation is effectively automatic.

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?

It gives an explicit when-to-use condition: the user asks how many credits remain. There are no exclusions or alternative routes mentioned, but for a single-purpose balance check none are plausibly needed.

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