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

With no annotations, the description carries the full burden and does disclose the critical trait: this is a paid call ($0.001, x402, USDC on Base), plus the data source (public RPC) and the return value (block height). It omits failure/retry behavior, cache/freshness, and rate limits, so it is strong but not exhaustive.

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 compact clauses, front-loaded with the cost — the first thing an agent must know before calling — followed by what is returned and how. No wasted sentences.

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?

For a zero-parameter, single-value tool with no output schema, the description covers cost, mechanism, and return type adequately. It leaves out edge behavior (payment failure handling, staleness) but nothing blocks a correct invocation.

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?

The tool takes zero parameters, so per the baseline there is nothing for the description to disambiguate. No parameter-level meaning is needed or missing.

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+resource ('get latest ... block height'), the chain (Base mainnet), and the underlying call (eth_blockNumber via public RPC). This clearly separates it from siblings like get_crypto_price, get_erc20_balance, or get_time, which all return different data.

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?

'Cheapest chain-tip probe for agents' frames the intended use case — fetching the chain tip cheaply. It gives clear usage context but names no explicit alternative or when-not condition, so an agent must infer that alternatives would be a costlier or differently-scoped probe.

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