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

Annotations already declare readOnly/idempotent/non-destructive/open-world, so the safety profile is covered. The description adds genuinely new behavioral facts the annotations cannot express: the exact chain set (7 EVM chains), a per-chain recommendation outcome, and the commercial constraints (10 calls/day free, then $0.002/call via x402 _meta or HTTP, or X-API-Key credits). What is not covered is failure semantics — whether unreachable endpoints are reported as down versus erroring the call.

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 in the first clause and every following clause carries load-bearing information (metrics measured, output, price, payment channels). The trailing '[served by tools.moneytools.dev]' is minor but the paragraph is dense with semicolon-separated pricing detail that could be slightly easier to scan.

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, return values need not be spelled out, annotations cover safety, and the one parameter is fully described. The description closes the remaining gaps an agent needs — cost, auth mechanism, and chain scope. Only error/timeout behavior and whether results are cached is left unstated.

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 coverage is 100% and the single optional 'chains' parameter already documents the comma-list format, the default (all 7), and an example. The description repeats the chain scope but adds no syntax or filtering detail beyond the schema, so 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?

Specific verb ('Probe') plus specific resource ('keyless public RPC endpoints of 7 EVM chains') plus the scope of what is measured (up/down, latency, head block, lag) and the return ('recommended RPC per chain'). That is enough to separate it from siblings like chain_info or contract_read without opening a schema.

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?

'right now' signals a live check rather than cached metadata, which is an implied when-to-use cue. However, the description never names an alternative or an exclusion (e.g. when to prefer chain_info for static chain data), so routing guidance is only implicit.

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