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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds genuinely useful behavioral context not in the annotations: 'Free: does not use a request,' which matters for quota-awareness. It stops short of describing return format/pagination but no output schema exists.

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, zero waste, with the return contents front-loaded ahead of the invocation guidance. Nothing extraneous.

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?

With zero params and no output schema, the description fully covers what the tool does and what it returns (plan, used, left, reset time) plus the cost note. An agent has everything needed to call it correctly.

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. The schema is empty and there is nothing for the description to compensate for; no confusion is possible.

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?

Names a specific verb ('Shows') and enumerates the exact resource fields returned: plan, requests used, remaining, and reset time. An agent can clearly distinguish this diagnostic tool from the analytics siblings (get_growth, get_time_series, get_top_posts, get_top_trends).

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 explicit trigger conditions: 'when the user asks about their limit' and 'after a limit error.' Clear invocation context. It doesn't name when-not-to-use or an alternative, but the siblings are unrelated analytics tools so an exclusion is less necessary.

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