UNDERSTANDING — Top-rated providers in a curated API Evangelist area. Priced B1 (single-entity synthesis) — $0.01 per call under pay-as-you-go; included in Understanding and Influence. See apis://prices.
| Name | Required | Description | Default |
|---|---|---|---|
| slug | Yes | Area slug, as find_areas returns it, e.g. "security". | |
| limit | No | Results per page, 1-100 (default 25). | |
| context | No | Optional: one sentence on why you are asking. Never used to rank; read only if a result is wrong. |
Changes observed during successful MCP inspections.
Input schema / properties / context / descriptionPrevious value: -"Optional: why you are asking. One sentence — the task you are trying to complete, or what you expect to get back. Never included in the answer and never used to rank; it is read only when a result turns out to be wrong, which is when knowing the intent is what makes the report actionable."New value: +"Optional: one sentence on why you are asking. Never used to rank; read only if a result is wrong."Input schema / properties / limit / descriptionAdded value: +"Results per page, 1-100 (default 25)."Input schema / properties / slug / descriptionAdded value: +"Area slug, as find_areas returns it, e.g. \"security\"."Input schema / properties / contextAdded value: +{
+ "description": "Optional: why you are asking. One sentence — the task you are trying to complete, or what you expect to get back. Never included in the answer and never used to rank; it is read only when a result turns out to be wrong, which is when knowing the intent is what makes the report actionable.",
+ "type": "string"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful non-schema behavior: the B1 pricing class, the $0.01 per-call cost, and which subscription tiers include it. It omits pagination and result-shape behavior, so it adds some but not rich context.
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 description leads with a packaging/marketing label ('UNDERSTANDING —') and spends more words on pricing tiers and price-page pointers than on what the tool does. The purpose sentence, which should be front-loaded, arrives second and is shortchanged.
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 3-parameter read tool with no output schema, the description covers cost and access tier but never explains what a 'leader' result contains or how pagination behaves with limit. The most expensive-to-guess behavior for an agent remains unaddressed.
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 100%, so the schema already documents slug, limit (range and default), and context; baseline 3 applies. The description contributes nothing beyond the schema about parameters, and notably does not reinforce that slug comes from find_areas even though the schema says so.
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?
The sentence 'Top-rated providers in a curated API Evangelist area' does state a resource and scope, so the core purpose is derivable. However, it is buried behind the 'UNDERSTANDING —' pricing label, and it gives no differentiation from the close siblings get_country_leaders, get_industry_leaders, and get_region_leaders, which are structurally identical.
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?
There is no when-to-use guidance, no prerequisites, and no routing to alternatives. The pricing/packaging note tells the agent what it costs but not when this tool is the right choice over the sibling leader tools.
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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