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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is fully covered. The description adds the genuinely useful fact that the call consumes no credits, and defines the unit ('one credit is one new lead'), which goes modestly beyond the annotations, though it says nothing about the shape or freshness of the returned balance.

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?

Three short fragments, all load-bearing: resource, cost, and unit definition. It is front-loaded and wastes nothing, though the telegraphic style (no main verb in the first fragment) is slightly terser than ideal.

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, fully annotated read tool with no output schema, the description covers what is returned (balance and plan), that it costs nothing, and what a credit means. An agent has enough to call it correctly; only the exact response fields are left unspecified.

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; baseline 4 applies. The definition correctly stays silent on inputs rather than inventing any.

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 the specific resource — Veezco credit balance and plan — so the agent knows exactly what it gets back. The verb is implicit in the tool name rather than the description, and no sibling differentiation is offered, but the siblings (list_categories, search_companies) are unrelated enough that confusion is unlikely.

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?

There is no explicit statement of when to call this versus alternatives or when not to. Usage is only implied by 'Free, no credits used,' which suggests it is safe to call at any time without cost, but the agent must infer that checking the balance before a credit-consuming action is the point.

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