tipo_de_cambioFetches today's official Costa Rican reference exchange rates from Hacienda, including USD buy/sell in colones and EUR in colones and dollars. Use it to convert amounts at official rates.
Tipo de cambio de referencia de hoy según Hacienda: dólar (compra y venta en colones) y euro (en colones y en dólares).
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the agent knows this is a safe external read. The description adds only the source (Hacienda) and the data composition, and says nothing about failure behavior when no rate has been published yet (weekends/holidays), timezone/date boundary of 'hoy', or caching/freshness of the fetch.
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?
A single sentence with the source and temporal scope front-loaded and the currency breakdown following. Every clause carries information; there is no boilerplate or redundancy.
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, the description correctly shoulders the burden of describing return content by listing the three rate pairs (USD buy/sell, EUR/CRC, EUR/USD). It stops short of stating the return shape or naming the currency codes, which leaves some ambiguity about how to parse the result, but the substantive coverage is solid for a no-argument lookup.
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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly makes no parameter claims and instead spends its words on output content.
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?
Names a specific resource ('Tipo de cambio de referencia de hoy') and its authoritative source ('según Hacienda'), then enumerates exactly which rates are included: USD buy/sell in colones and EUR in colones and dollars. An agent can tell immediately that this is a single-purpose FX lookup, and the sibling tools (taxpayer lookup, CABYS codes, exoneration) are clearly unrelated, so no differentiation is needed.
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 'de hoy' establishes the temporal scope and implicitly tells the agent this tool only answers today's reference rate, not historical series. There are no sibling alternatives to route between and no prerequisites to state, but the description never explicitly says 'use this when you need a current exchange rate for a calculation' or excludes anything.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.