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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description's 'Get' wording is consistent with those. It adds non-obvious behavioral context by disclosing the $0.005 USDC x402 payment and specifying that the result includes header and transaction hashes, not full transaction bodies. This is useful for an agent deciding whether to invoke the 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?

The description consists of two tight sentences with the core operation front-loaded. The cost sentence is necessary information and not filler. Nothing could be removed without losing meaningful guidance.

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 tool with no output schema, the description provides the essential facts: what to fetch, what it returns, and the payment cost. The mention of 'header and transaction hashes' serves as a return-value statement. It does not explain behavior when `block` is omitted, which is a minor gap given the schema lists no required fields, but the description is otherwise largely complete.

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 for the sole parameter `block` is 100%, so the schema already explains that it accepts a block number or a tag such as latest, safe, finalized, pending, or earliest. The description only repeats the notion of 'number or tag' and adds no new parameter-level detail. The baseline of 3 applies because the schema carries the full semantic weight.

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 starts with a specific verb, 'Get', and names the resource, 'Base block', with scope qualifiers 'by number or tag' and result details 'header and transaction hashes'. This clearly distinguishes the tool from siblings like base_transaction or base_block_number, even though those alternatives are not named explicitly.

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 description gives no guidance about when to choose this tool over base_transaction, base_block_number, or base_receipt, and it states no exclusions or prerequisites. The only additional context is the cost notice, which is payment information rather than a usage rule. The intended use case must be inferred from the tool's name and purpose statement.

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