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

The description discloses that the tool is a preview (not a mutation) and is free (no credits required), adding behavioral context beyond the absent annotations. However, it does not mention authentication needs (npub, dpop_token) or any rate limits.

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 three sentences long, front-loads the main purpose, and contains no wasted words. Every sentence adds value.

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 and the presence of an output schema, the description provides adequate purpose and behavioral info. However, it lacks details on parameter usage and optional inputs, which would help the agent use 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 schema description coverage at 50%, the description does not add any meaning to the parameters beyond what the schema provides. It does not explain the purpose of npub or dpop_token, nor the usage of tool_kwargs for pricing preview.

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 tool previews the effective cost of a tool call, using a specific verb ('preview') and resource ('cost of a tool call'). It distinguishes this from sibling tools like weather_check_balance and weather_check_payment by focusing on cost preview.

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 implies usage when the agent needs to know the cost of a tool call before executing it, but it does not explicitly state when to use this tool versus alternatives, nor does it mention when not to use it.

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