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

With no annotations, the description carries the full burden. It discloses 'No auth' and lists the returned fields, which is useful, but it does not explicitly state that the operation is read-only, whether it has rate limits, or any other safety profile. It covers some behavioral ground but leaves obvious gaps for a no-annotation tool.

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?

A single sentence with no waste, front-loaded with the core resource and output fields. Every clause earns its place, including the brief 'No auth' note.

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 one-parameter, read-only status tool with no output schema, the description is largely complete: it explains the returned fields and the no-auth behavior, and the schema covers parameter handling. It could mention error/refusal behavior explicitly, but the schema already documents that.

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 schema's chain parameter description is extremely detailed (accepted spellings, defaults, refusals). The tool description adds no meaning beyond what the schema already provides, so the baseline of 3 is appropriate.

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 (one chain's sync status) and enumerates exactly what it reports: indexer head, safe/finalized blocks, lag in blocks, and freshness_seconds. It is clearly distinct from all sibling tools, which deal with addresses, transactions, and sanctions, not chain indexer state.

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 clause 'so the agent knows how recent the data behind an answer is' gives clear context for when to call it: to assess data staleness before relying on other results. It does not state when-not to use it or name alternatives, but the context is explicit and sufficient.

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