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

Beyond the readOnly/idempotent/non-destructive annotations, the description adds substantive behavioral context: the credit-to-video exchange rate (a video costs 10), that extra credits are user-selected, and critically that payment and plan changes must happen via the returned link because the agent cannot perform them. This is exactly the constraint an agent needs and is not in any annotation.

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 dense sentences, front-loaded with the return contents and closed by the key action-permission constraint. Every clause carries information (prices, credits, 10-per-video, extra-credit pricing, payment link, no self-purchase) with no filler.

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 no output schema, the description carries the burden of explaining returns, and it largely does by listing plan contents. Low tool complexity (zero params, read-only) means little else is needed. It could be marginally richer about the output shape, but it is essentially complete.

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?

Zero parameters, so there is nothing to document and no schema gap to compensate for. The baseline for a parameterless tool applies; no wasted parameter prose.

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 enumerates exactly what the tool returns: monthly/yearly prices, credits per month, connected accounts, plan inclusions, and extra-credit pricing. This is a specific resource scope an agent can recognize. It stops short of naming which sibling it is not (e.g., get_account or get_catalog), so no explicit differentiation.

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?

Usage is only implied by the content description (fetch when the user asks about plans/pricing). There is no explicit when-to-use clause or routing away from alternatives like get_account. The 'you can't pay or change the plan yourself' note hints at the downstream workflow but is not framed as usage guidance.

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