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

Annotations already provide readOnlyHint, idempotentHint, destructiveHint. Description adds that it takes no arguments, is free, and requires no API key. It describes the output but does not explicitly state whether calling it consumes rate limits, which could be inferred as safe but is not confirmed.

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 sentences: first describes output, second gives usage advice, third states no arguments and free. Concise, front-loaded, and each sentence adds value.

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?

Given no parameters and no output schema, the description provides essential usage advice and output description (tier, burst, allowance, billing). It could be more specific about output format or whether it reports current usage vs limits, but is generally complete for an agent's decision-making.

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 exist and schema coverage is 100%. The description explicitly states 'Takes no arguments', confirming the absence of input, which is sufficient.

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 clearly states that this tool returns the credential's allowed usage: tier, burst, allowance, and billing. It also advises when to use it to avoid rate limits, and distinguishes it from sibling tools which deal with permits, gates, requirements, and jurisdictions.

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?

Explicitly advises to call at the start of a long task to pace usage, contrasting with encountering rate limit errors. Also notes it is free and requires no API key, offering clear guidance on when and how to use.

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