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

The readOnlyHint annotation already covers the safety profile, so the bar is lower. The description still adds real context beyond it: the tool costs nothing to call ('Free'), and it discloses the accepted payment methods (card/Apple Pay/USDC) plus the pass types covered, which tells the agent what kind of information it will get back.

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 compact sentences with no filler; the subject (pricing and purchase links) is front-loaded and the trailing 'Free.' answers the cost question an agent would otherwise have to ask.

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, read-only informational tool with no output schema, the description adequately covers what the agent gets and that it is free. A brief note that the response is static reference content rather than live inventory would close the remaining gap.

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. The description correctly implies there is nothing to supply — no account, plan, or pass identifier is needed to retrieve the pricing information.

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 names a concrete resource — pricing and purchase links for 30-day feed passes and x402 day passes — so an agent immediately knows this is the billing/access-info tool rather than a data feed. It is clearly distinguishable in practice from the sibling feed tools, though it never explicitly contrasts itself with them.

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: an agent infers it should call this when a user asks how to buy access or what a pass costs. There is no explicit when-to-use statement, no exclusions, and no named alternative (e.g., a support or docs tool).

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