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

Annotations already declare readOnlyHint=true and openWorldHint=true, but the description adds genuinely useful behavioral context they cannot carry: metered pricing ($0.002 USDC per call via x402 or prepaid credits) and a free trial. 'Live ... right now' is also consistent with idempotentHint=false, signaling the response is time-varying.

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 core capability is front-loaded in the first sentence, and the chain/fee enumeration follows. There is mild redundancy — the $0.002 price is in both the title and the description body — but overall the text is dense and largely earns its place.

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 an output schema present, the description need not explain return values, yet it still outlines them (fee tiers, congestion/trend, USD cost per operation, cheapest chain). Combined with the annotations covering safety and the schema covering the parameter, an agent has everything needed to invoke it correctly.

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 sole optional 'chains' parameter is fully documented in the schema (including the exact slug list). The description's chain enumeration corroborates the schema but adds no syntax or format detail beyond it, so the baseline 3 applies.

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+resource with unusual precision: 'What a send, token transfer or swap costs right now on each major chain, and which chain is cheapest,' and enumerates the covered networks. It does not, however, explicitly differentiate itself from siblings like token-price or trade-precheck, so it stops 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 implied by the framing ('what a send... costs right now'), which tells an agent to call this before a transfer or swap. There is no explicit when-to-use vs. when-not guidance and no named alternative tools, leaving the routing inference to the agent.

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