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

With no annotations present, the description carries the full behavioral disclosure burden. It conveys that this is a public lookup requiring no key, which meaningfully hints at a safe read-only operation. It does not describe response formatting, but the expected behavior is simple and adequately conveyed.

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?

The description is two short sentences with no filler. The main subject (plans and per-tier limits) is front-loaded, and the practical auth detail is appended efficiently.

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 informational tool with no output schema, the description is largely complete: it states what is returned and that no key is required. A more explicit statement of the return format would improve it slightly, but nothing essential for invoking it correctly is missing.

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 accepts zero parameters, and the empty input schema fully documents that. The description adds useful context about what information is returned, so no parameter explanation is needed.

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 identifies the resource as pricing plans and per-tier limits, naming the specific tiers (free, dev, pro). It lacks an explicit verb like 'retrieves' or 'lists,' but the intent is unambiguous and distinct from the sibling 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?

The description provides clear context for when this tool is relevant: when a user needs plan information or tier limits. The note 'No key required' adds practical usage guidance by indicating authentication is not a prerequisite, though it does not explicitly contrast this tool with alternatives.

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