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

Annotations already cover read-only, idempotent, non-destructive and non-open-world behavior, so the bar is lower. The description adds genuinely new information: authentication is required, and unauthenticated invocation only returns signup/connect instructions rather than data — a meaningful behavioral caveat. It still says nothing about pagination or result size.

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 short sentences, front-loaded with what is listed before the authentication caveat. The second clause ('here it only explains how to sign up and connect') is slightly awkwardly phrased but still earns its place by preventing a false expectation of data.

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 indicating what comes back, and the enumerated entity types largely do that. Combined with the annotation-derived safety profile and the disclosed auth requirement, an agent has enough to call and interpret this 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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. It correctly implies a no-argument, account-scoped listing rather than suggesting any filter inputs.

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?

States a specific verb (List) and resource (Frely account contents) and enumerates the entity types returned: API keys, Credit, plans, orders, Creator items. It is distinguishable from siblings such as list_devices and models_list by scope, though it never explicitly names an alternative.

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 second sentence implies the usage condition: the call requires sign-in and otherwise degrades to signup/connection instructions. That is useful context, but no explicit when-to-use-vs-alternative guidance is given (e.g. how it differs from frely_about), so usage is only implied.

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