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

Annotations cover safety (readOnly, non-destructive) but the description adds the operational facts: per-item failure semantics, one charge if at least one item succeeds, Base-only payment, and that a failed call is not charged on Base but may be on other rails. It also explains partial failure handling, consistent with idempotentHint=false since each retry re-charges.

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?

Front-loaded with purpose, then wire format, return shape, and economics; nothing is pure filler. The price-per-item arithmetic across four different quantities is more verbose than needed and could collapse into a single break-even sentence.

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?

Despite having no output schema, the description specifies the response shape (results array with index/route/status/ok/body, plus count and okCount) in request order. Combined with cost, failure handling, and payment rail, an agent has everything required to call this correctly on the first try.

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 already documents route and params, so the description only needs to reinforce meaning. It does add the GET form ('items=<same JSON>') and clarifies that params are the 'single route's query keys', which helps an agent construct valid nested payloads, though it largely restates the schema's own route list.

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 and resource ('Batch chain checks API: up to 10 checks for one payment') and immediately names the exact routes that can be batched, which maps directly onto the sibling tools (balance, gas, tx_status, token_meta, chain_head, name_resolve). An agent can tell this is a fan-out wrapper around single-route reads without opening the 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?

Gives explicit alternatives ('the same single routes at $0.002 each, or public RPCs and block explorers') and the precise break-even rule: below 5 items singles are cheaper, at 5 they tie, above 5 batch wins. That is exactly the decision an agent needs to route between this and its siblings.

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