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

With no annotations provided, the description carries the full burden. 'Retrieve' implies a read-only operation but does not explicitly state that no data is modified or that it only reads usage data. It adequately conveys the non-destructive nature via the verb 'retrieve', but lacks explicit safety statements or any discussion of potential side effects (none expected).

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 concise: one main sentence followed by two bullet points. It front-loads the purpose, and every sentence adds value. No redundancy or unnecessary detail.

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 the tool's simplicity, an output schema is present (so return values are covered), and the description clarifies both the function and appropriate usage. Nothing critical is missing for an agent to correctly invoke this getter tool.

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 schema provides a full description of the api_key parameter, including its optionality and alternative authentication methods (header or env var). The description does not add extra meaning beyond that, so the baseline of 3 for full schema coverage is appropriate.

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 action (retrieve) and the resource (plan features and usage limits) for a specific subject (your API key). It is distinct from all sibling tools, which focus on datasets, projects, monitors, and webhooks, not user limits.

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 'Use when' section explicitly lists two concrete scenarios: checking plan allowances and verifying usage before running a large job. This gives clear guidance on when to call the tool, and because no sibling tool covers the same functionality, alternatives are unnecessary.

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