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

Beyond the readOnlyHint annotation, the description discloses that the call itself consumes 1 unit, which is critical behavioral information for an agent deciding whether to invoke it. It also transparently describes the anonymous/no-key fallback behavior, adding real value beyond the structured annotations.

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 and front-loaded: it states what is returned first, then the self-consumption quirk, then the anonymous fallback. Every sentence provides distinct, useful information without repetition or fluff.

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?

Although there is no output schema, the description enumerates the returned data points (plan, daily quota, used units, remaining units) and covers the authentication fallback and unit cost. An agent has everything needed to invoke the tool 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?

With zero parameters and an empty input schema, the description's statement 'Aucun paramètre' matches the schema exactly. There is nothing more to explain, so the baseline for no-parameter tools 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 states the resource (Propecto API key quota), the action (indicates plan, daily quota, used and remaining units), and explicitly notes there are no parameters. This distinguishes it from sibling tools that operate on companies, markets, finances, etc., so an agent can recognize it uniquely.

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 gives clear context for when this tool applies: checking the API key quota and usage. It also explains the behavior without an API key, which is useful decision-making context. It does not explicitly name alternatives or exclusions, but for a standalone quota endpoint this is not a significant gap.

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