Get official South African regulated fuel prices (95 ULP, 93 ULP, 50ppm Diesel) from the Central Energy Fund (CEF), including next price adjustment date and projected change.
| Name | Required | Description | Default |
|---|---|---|---|
| region | No | South African price zone (Inland or Coastal). | |
| fuel_grade | No | Fuel grade to query (default: Petrol 95). |
Changes observed during successful MCP inspections.
Input schema / properties / region / descriptionPrevious value: -"South African price zone (Inland or Coastal). [Optional: omit to use server default filter]."New value: +"South African price zone (Inland or Coastal)."Input schema / properties / region / descriptionPrevious value: -"South African price zone (Inland or Coastal)."New value: +"South African price zone (Inland or Coastal). [Optional: omit to use server default filter]."Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It usefully discloses the authoritative source (CEF) and that the response includes the next adjustment date and projected change, but it does not state freshness, caching, rate limits, or error behavior.
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 front-loaded sentence that states the resource, grades, source, and included extras with no wasted words.
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?
For a no-annotation, no-output-schema tool, the description covers purpose and source but does not describe the return format, units, currency, or the structure of the projected-change data, leaving some gaps an agent would need to discover by calling it.
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 both parameters are already documented with enums and defaults. The description lists fuel grades but adds no syntax or format beyond the schema, so the baseline 3 is appropriate.
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 — official South African regulated fuel prices — names the exact data source (CEF), and enumerates the three covered grades. It is clearly distinguishable from sibling tools like list_fuel_logs.
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 implies when to use it (official regulated price lookup) and names the source, but it gives no explicit when-not guidance or alternative tools for related tasks like viewing historical fuel logs.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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