compare_gateway_fees

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

The tool is read-only, and the description emphasizes evaluation and comparison with no side effects. However, it does not explicitly state that it makes no modifications or external calls, which could be worth mentioning for full transparency. The absence of side-effect annotations is offset by the clear intent.

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 concise, composed of two sentences that cover the input, the process, and the output. No redundant or extraneous information is included. It is well-structured and easy to read.

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?

The description fully explains the tool's purpose, inputs (amount and currency), and outputs (itemized fee breakdown and recommended provider). Since there is no output schema, the description adequately covers what the caller should expect. No critical information about the tool's behavior is missing.

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 schema descriptions for both parameters are highly detailed, providing units (minor currency units), examples, and valid currency codes. The tool description adds no extra parameter information but relies on the schema, which is already comprehensive. Since schema coverage is 100%, a baseline of 3 is appropriate, but the schema's clarity raises the score to 4.

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's function: comparing transaction fees across Stripe, Razorpay, and LemonSqueezy for a given amount and currency. It distinguishes itself from sibling tools that handle payment link creation, webhooks, analytics, itemized invoices, and refunds, making its specific purpose unambiguous.

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 implicitly indicates when to use this tool—whenever a fee comparison across these gateways is needed. It does not explicitly contrast with alternatives, but the distinct purpose and the mention of the recommended lowest-cost provider make the usage context clear. A brief note on when not to use it would have earned a 5.

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