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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the bar is lower; the description adds cost context ('before you spend anything', 'Free') and discloses the per-entry payload contents. It does not mention auth requirements or pagination, minor gaps against an already-covered safety profile.

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?

Purpose is front-loaded, then payload contents, then cost. The long enumeration of data domains is dense but earns its place for a catalog tool; a tighter grouping could have shortened it slightly.

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 carries the return-value burden and does so fully — it lists the exact fields of every entry and confirms the call is free, giving the agent everything needed to call and consume 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?

Zero parameters, so the baseline is 4. The description usefully explains what each returned catalog entry contains (price per call in USDC, return payload, example question, parameters with valid values, sample URL), which compensates for the absent output schema.

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?

Specific verb+resource ('List every paid Frontera Signal endpoint') with an explicit scope statement ('before you spend anything') that separates it from the free-access siblings like get_sample and how_to_pay. The enumerated data covers make the resource unambiguous.

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?

'before you spend anything' clearly signals the discovery/pre-purchase context, and 'Free' tells the agent this call itself costs nothing. It does not name a sibling as an alternative or state exclusions, so it falls short of a 5.

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