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

Annotations already cover readOnly/idempotent/non-destructive, so the description correctly spends its budget elsewhere: it discloses that results are 'indicative' rather than binding, that the quote includes fee, mid-market rate, total cost and typical delivery time. It stops short of stating what happens for unsupported corridors or invalid currency pairs, which would be the remaining useful behavioral detail.

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 what is returned, then when to use, then how to present. Each sentence carries a distinct job (output content, invocation condition, user-facing framing) with no padding.

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?

There is no output schema, yet the description enumerates the returned fields (amount sent, fee, mid-market rate, recipient amount, total cost, delivery time), so an agent knows what it will get. Combined with the prerequisite and disclaimer instructions, nothing an agent needs to call and correctly present this tool 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?

Schema coverage is 100% and each parameter already carries a precise description including defaults and ISO codes, so baseline is 3. The description reinforces the sender/recipient-account framing and the 'do not assume where the user lives' caveat, but the schema already states that instruction verbatim, so it adds little beyond restatement.

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 concrete verb+resource ('Returns an indicative quote for sending money') and immediately scopes it: sender in from_country to a recipient's bank account in to_country. This is clearly distinguishable from get_exchange_rate (rate lookup) and list_send_destinations (corridor availability), which the description also names.

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?

Explicitly says when to use it ('to answer how much a transfer costs or how much will arrive'), names a prerequisite ('Use list_send_destinations first to check the destination is offered'), and prescribes post-call behavior (present figures as indicative, point to get_started_url). When-to-use, ordering, and follow-up are all covered.

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