Check credits and recent charges

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

Annotations declare readOnlyHint=true. Description adds significant behavioral context: free, exempt from rate limit, works across account types, includes upgrade_url, manage_url, claim_url. No contradictions.

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?

Description is informative but slightly long. Each sentence adds value: purpose, cost, usage guidance, response details, caveat. Could be more concise but well-structured.

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?

Tool has no parameters, simple. Description covers output (charges, URLs), usage scenario, and account types. Has output schema to fill remaining details. Complete enough for reliable use.

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?

No parameters. Schema coverage 100% trivially. Description adds no param info but none needed. Baseline for 0 params is 4.

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?

Description clearly states tool checks balance, plan, limits, and last 10 charges. Verb 'check' is specific. Explicitly distinguishes from sibling tools by stating 'Not for fetching platform data', which are social media tools.

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 strategic guidance: 'call it first to check your budget before running data tools, and any time after'. Notes it costs 0 credits and exempt from rate limit. No direct alternatives among siblings, so no when-not needed.

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