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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds meaningful non-obvious context: the result is an estimate and final terms appear in the Poplin app, which tells the agent how to frame the answer. It does not discuss rate freshness or fee breakdown structure, keeping it below a 5.

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?

Three sentences, front-loaded with the core estimate and followed by the usage trigger and estimate caveat. Minimal waste, though the pricing/account-type clause slightly crowds the opening sentence.

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?

No output schema exists, but the description tells the agent what the result contains (rate, fees, deposit limits) and warns it is non-binding. The main remaining gap is the ambiguity over which currency the amount is expressed in, which an agent could misread.

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?

Schema description coverage is 0%, so the description must carry parameter meaning. It implies currency is the source payment currency ('such as EUR or GBP') but never clarifies that amount is denominated in that source currency, nor that currency follows ISO-4217 format. Partial compensation only.

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?

States a specific verb ('estimates') and a precisely scoped resource: the USD amount received when a payment arrives in another currency, including rate, fees, and deposit limits. The inbound direction ('pays into its receiving bank account') clearly distinguishes it from the sibling get_send_quote.

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?

Gives a concrete usage trigger ('Use it when someone asks what they would receive for a payment in a currency such as EUR or GBP') with examples. It stops short of explicitly naming get_send_quote as the alternative for outbound quotes, leaving that inference to the agent.

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