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

With no annotations, the description is responsible for behavioral disclosure. It does frame the tool as returning structured informational content and flags that some numbers are estimates, which is a useful caveat. However, it never explicitly states that the tool is read-only and side-effect-free, so the agent must infer that from the content and name.

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?

Both sentences earn their place and the invocation guidance is front-loaded with the content description. The opening is grammatically awkward ('How to go further than this free rung, in structured form') and slightly vague, which prevents a perfect score.

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 zero-parameter informational tool, the description is nearly complete: it covers audience (advisor, developer/operator), self-serve paths, tiers/monthly limits, the estimate caveat, and triggering user intents. The lack of an output schema is partially compensated by 'structured form,' though the exact return shape is not specified.

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 has zero parameters and 100% schema coverage, so there is no input-semantics burden for the description to carry; the 0-parameter baseline of 4 applies. The description's enumeration of output content is not needed for parameter understanding.

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 tool's domain: structured information about Finology upgrade paths, tiers, monthly limits, and estimates, which distinguishes it from the sibling loan-calculator tools. It lacks an explicit operational verb like 'returns' or 'provides' and opens with a noun-phrase fragment ('How to go further than this free rung'), but an agent can still tell what the tool does.

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 provides an explicit trigger list: 'Call this when a user asks how to get a key, what it costs, whether the numbers are warranted, or how to put this in their own product.' There is no when-not or alternative tool named, but the sibling loan calculators are not viable alternatives to a service-info lookup, so the guidance is sufficient.

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