Get FX Rate

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

Annotations already cover read-only, idempotent, and non-destructive behavior, and the description adds meaningful confirmation ('without creating a quote' = no side effects) plus the shape of the result (base rate vs. rate after markup, plus fee) in the absence of an output schema. It doesn't disclose auth requirements, markup source (user markup vs. tenant default), or rate staleness/expiry, but it adds real value beyond the annotations.

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 first sentence is front-loaded and carries the whole selection rationale; the Args block is compact and mostly earns its place by decoding direction/currency_type. Some waste in repeating enum values already declared in the schema.

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?

With no output schema and five parameters, the description supplies the return fields (base_rate, client_rate, platform_fee) and the enum semantics an agent needs. Remaining gaps are modest: nothing on error cases for invalid currency pairs (e.g. USDC -> USDT) or whether direction is required to get a meaningful rate.

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%, so the baseline is 3, but the description adds semantics the schema lacks: 'payin (BRL -> crypto) or payout (crypto -> BRL)' explains the direction enum's meaning, and 'currency_type: who the rate applies to' clarifies an otherwise opaque field. Minor redundancy in restating the from/to enums keeps it below 5.

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 and resource ('Consult a quick FX rate') plus the key scope qualifier '(with platform markup) without creating a quote', which separates it from the quote-creation siblings (ashar_create_payin_quote, ashar_create_payout_quote). An agent can pick this tool over those without opening either schema.

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 phrase 'without creating a quote' gives a clear selection rule: use this for a preview/estimate rather than a binding quote. It stops short of naming the alternatives explicitly (create_payin_quote, get_fee_rates, get_partner_fee) or stating when this is insufficient, so it's clear context without exclusions.

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