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

The annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so safety and repeatability are covered structurally. The description adds a genuinely useful non-schema fact, 'Free', which tells an agent this call is costless and safe to probe early. It says nothing about response size, pagination, or whether the list is stable across calls, so it stops short of rich behavioral 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?

Two short sentences, front-loaded with the purpose and followed immediately by the call-ordering advice and cost note. Every clause carries information; nothing is redundant with the title.

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?

There is no output schema, so the description carries some burden for return content; it mentions assets, product ids, and prices, which covers the essentials for a zero-argument discovery tool. It could be slightly stronger by stating the shape of a returned entry, but against annotations that already cover safety it is close to complete.

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?

With zero parameters, the baseline is 4; there is no argument surface to document. The description does useful extra work by tying the returned `asset` values to the input vocabulary of get_trend/get_regime, effectively documenting the output-to-input contract.

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 supported crypto assets and product ids') and scopes it to a named service, signal-api. It also names the concrete downstream consumers (get_trend/get_regime), which lets an agent place the tool precisely among the siblings.

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?

It gives an explicit ordering directive ('Use this first') plus the condition that selects it: discovering valid `asset` values for get_trend/get_regime. It does not address the closest sibling, get_catalog, so an agent must still infer which discovery tool to prefer in that overlap.

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