My Plan

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior, so the description does not need to restate those. It adds useful context: the tool shows every tier's limits and mentions X-RateLimit-* headers as the source of live remaining-quota counts.

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 compact: one sentence defines what the tool returns, and one sentence gives clear usage timing plus a useful note about rate-limit headers. No filler or redundancy.

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 simple read-only utility with one optional parameter, the description fully covers what the agent needs: the output contents, when to invoke it, and additional context about rate-limit headers. The lack of an output schema is compensated by the explicit listing of return data.

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?

Schema description coverage is 100% and the single optional boolean parameter is fully documented in the schema. The tool description does not add parameter-level detail, but it does not need to because the schema already covers it.

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 uses a specific verb ('Show') and identifies the exact resource: the current API key's plan. It gives concrete content details (tier, rate limits, all tiers' limits) and is clearly distinct from the many market/analytics 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?

It explicitly says when to use: when the user asks what plan they are on or after a tier/rate-limit rejection. It does not name alternatives, but none of the siblings appear to cover plan information, so the guidance is clear enough.

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