Get CaptchaNo balance

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds value beyond them by disclosing that the call is free (no spend incurred), that the returned spend figure is session-scoped, and that it is compared against an environment-configured cap — behavioral context the annotations do not carry.

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, both earning their place: the first front-loads what is returned, the second states when to call it. No filler, no repetition of the title.

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?

Zero parameters, an output schema that already documents the return shape, and annotations covering the safety profile — the description supplies the remaining needed context (cost-free, session-scoped spend, the limit it is measured against, and trigger conditions). Nothing an agent needs to invoke it correctly is absent.

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 the baseline is 4 and there is no parameter semantics the description could add or omit. Nothing here is misleading or missing.

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 (return) and resource (CaptchaNo account balance in USD), plus a second scope detail — session spend against the optional CAPTCHANO_MAX_SPEND_USD limit. It is unmistakably distinct from the siblings solve_captcha, get_task, and list_captcha_types, none of which report account state.

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 two concrete, actionable triggers: before a large batch of solves, and after an insufficient_balance error. That is clear contextual guidance, though it never names an alternative tool or states when not to call it, keeping it short of a full 5.

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