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

Adds a genuinely useful behavioral fact not present in annotations: a fixed $0.01 charge per call. That is important since readOnlyHint=false makes it non-obvious the tool costs money. It doesn't disclose return shape or whether repeated calls re-charge, but annotations already carry idempotency and destructiveness hints.

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?

Two short sentences, front-loaded with the action and dimensions, followed by the pricing fact. The second sentence is a bit marketing-flavored but still conveys use context, so little is wasted.

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 two-param tool with no output schema, the description should hint at what the comparison returns (per-model breakdown? ranking?), and it does not. The pricing and cardinality notes are helpful, but an agent still cannot anticipate the response.

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 0%, so the description must compensate. "Two or more models" usefully conveys the array cardinality constraint, and "fit for a task" maps to the optional task param. However, it never says whether model entries are names, IDs, or provider-prefixed strings, leaving a real ambiguity.

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 (compare) and resource (models) plus the comparison axes: price, context window, and task fit. An agent can distinguish it from fikra_list_models or fikra_get_tool_prices, though the description doesn't name those siblings explicitly.

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?

"Choosing a model without reading five pricing pages" implies the use case (model selection), which is helpful framing. But there is no explicit guidance on when to use this versus fikra_estimate_inference_cost or fikra_list_models, and no preconditions such as valid model identifiers.

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