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

With no annotations provided, the description carries the burden of behavioral disclosure. It usefully discloses that no API key is required and clarifies the free tier's authentication semantics. It does not describe output format or additional behavior, but this is a simple informational tool, so the disclosure is adequate.

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 short sentences with no filler. The core purpose is front-loaded, and the additional authentication nuance earns its place by preventing a common misunderstanding about what 'free' means.

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?

The tool is low-complexity with no parameters and no output schema, so the description does not need extensive detail. It includes the critical context that no API key is required and clarifies the free access model. A small gap is the lack of any statement about the return format, but 'public plan limits and entitlements' sufficiently implies the content.

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 has zero parameters and the input schema is empty, which gives a baseline of 4. The description does not need to explain parameter meaning because there are none; the 'No API key required' note adds relevant usage context beyond the schema.

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 and resource: 'Describe public plan limits and entitlements.' The word 'public' helps distinguish it from sibling tools like get_plan, though it does not explicitly name any sibling. Overall the purpose is clear and not a tautology.

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?

'No API key required' gives a clear condition for using this tool without authentication, and 'Free is authenticated real access, not anonymous data access' clarifies a key distinction. However, it does not explicitly state when to prefer this tool over alternatives such as get_plan or describe_authentication, leaving some routing to inference.

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