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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds meaningful context beyond that by disclosing that each entry includes the cheapest paid plan in US dollars and a free-plan indicator, which tells the agent what the data set contains rather than just that it is a read.

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?

It is a single well-formed sentence with no filler. The core action is front-loaded and the return content is appended in a natural order.

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 has to convey what a result looks like, and it does so by naming the price and free-plan fields. It stops short of describing ordering, pagination, or how the optional category filter affects output, which are minor gaps for a small read-only catalog tool.

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% and the single category parameter already carries an enum with a description, so the schema does the heavy lifting. The description's parenthetical ('video & avatar') adds only marginal detail, such as implying avatar tools fall under the video category; 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?

The description states a specific verb and resource ('List the AI tools GenCost tracks') and enumerates the covered categories, so an agent knows exactly what comes back. It does not distinguish itself from siblings like compare_tools or find_cheapest, which keeps it short of a 5.

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?

Usage is only implied: this is the catalog-enumeration tool, so an agent can infer it is the right first call when it needs the set of tracked tools. There is no explicit when-to-use or when-not-to-use guidance, and no mention of alternatives such as find_cheapest for price-focused queries.

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