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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The word 'Measured' hints the values are observed rather than guaranteed, which is useful context, but the description never says whether this is a static snapshot or a live probe, or how fresh the measurements are.

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 sentences, no filler, with the data-domain summary front-loaded and the parameter note second. The opening is a verbless noun phrase, which is slightly less scannable than a verb-first statement, but nothing is wasted.

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 no output schema, the description carries the burden of describing return shape; it partially does so by enumerating the four measured dimensions, which is genuinely helpful. It still omits the response structure, how many endpoints are covered, and whether results are cached — gaps an agent would notice on first call.

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 schema already documents 'Chain id or slug, e.g. 1 or ethereum', so the description repeats rather than extends it. The one added nuance is that the parameter filters rather than selects — implying an unfiltered call returns all chains — but that inference is left implicit.

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 names a specific resource — measured eth_getLogs limits, latency, archive support and error messages — for free public RPC endpoints, which makes the tool's output domain unambiguous. It lacks an explicit verb (is it 'get', 'compare', 'list'?) and does not reference either sibling, though the siblings are far enough away in domain that confusion is unlikely.

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?

The only guidance is 'Pass chain (id or slug) to filter,' which is a parameter instruction rather than a when-to-use rule. Nothing tells the agent when this beats querying an endpoint directly, whether it covers only free/public providers, or what happens if chain is omitted.

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