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

No annotations are provided, so the description carries the burden. It states the tool is 'free' and describes querying accepted coins and schemes, implying a read-only operation. It could explicitly note it has no side effects, but the description is sufficiently transparent about what the tool does.

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 detailed and well-structured, front-loading the purpose and then listing payment methods. While every sentence adds value, it is slightly verbose; a bit more conciseness would improve it.

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 zero parameters and no output schema, the description provides a complete picture: what the tool does, its output (coins and schemes), how it relates to sibling tools, and the free nature. No missing information for effective use.

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?

There are zero parameters, and schema coverage is 100%. The description adds value by explaining what the tool returns (list of coins and schemes) and how that output is used in the broader payment context, compensating for the lack of output schema.

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 lists 'which coins and schemes this gateway accepts for payment.' It uses a specific verb (lists/which accepts) and resource (payment options), and distinguishes from sibling tools by explaining how each payment method works and when to use 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?

The description explicitly provides usage guidelines: it explains three ways to pay (prepaid session, per-call, covenant channel), mentions alternatives like open_session and pay_per_call, and gives context for when each method is appropriate.

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