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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds one non-obvious behavioral detail – that the result carries a signed receipt – but does not explain what that receipt is or how it should be used, so the added context is thin.

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 tight sentences with the resource and returned fields front-loaded and no wasted prose. The trailing sentence about the signed receipt is slightly vague but earns its place by flagging a return-value trait.

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?

An output schema exists so return values need no explanation, and annotations carry the safety profile; the description covers what the tool reads and its default scope. Only the ambiguous 'signed receipt' phrase leaves a small gap in what an agent should expect.

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?

With a single parameter at 100% schema description coverage, the schema already fully documents accepted hex/decimal/tag formats and the default. The description only restates 'latest or a given block' and adds no format or constraint detail beyond the schema.

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 concrete resource (block header) and enumerates the returned fields (number, timestamp, transaction count, base fee) plus the scope (latest or a given block). It does not name a sibling such as tx_activity, but the purpose is unambiguous.

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?

'for the latest or a given block' implies the default behavior, and the schema confirms defaults to latest. However, there is no explicit when-to-use guidance or differentiation from related tools like tx_activity, leaving routing to inference.

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