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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that by stating 'Costs nothing,' which addresses the cost concern an agent or user would have before invoking. It does not describe the shape of the returned content, but for a zero-parameter informational tool the added cost disclosure is meaningful.

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?

Information is front-loaded and every clause carries content: the resource, the return contents, the trigger conditions, and the cost. The opening sentence is a long enumerated list, which is slightly dense, but there is no filler or repetition.

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 simple zero-parameter guidance tool with no output schema, the description fully covers what the agent needs: what will be returned (link, steps, price, key setup) and when to call it. No gaps remain that would cause a misinvocation.

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 no parameters and has 100% schema description coverage, so the schema baseline applies. There is nothing parameter-related for the description to add or omit.

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 spells out exactly what the tool returns: the signup link, the steps the person must take themselves, the price, and how to add the key to this connector. That specificity makes it trivially distinguishable from siblings like arvx_record_summary and arvx_run_reading, which are data-retrieval tools.

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 gives two explicit trigger conditions: 'Call this when there is no key, or when the person asks how to start.' No inference is required about when to invoke it, and the conditions are precise enough to act on directly.

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