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

Annotations declare readOnlyHint=false, which is otherwise puzzling for a pure read; the description resolves this by explaining 'not marked read-only because each call is charged.' It also discloses the 400-on-malformed-address behavior, that such failures are uncharged, pricing ($0.003/call, first 25 free), and that failed calls are free — all beyond what annotations provide.

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?

Purpose and scope are front-loaded in the first sentence, followed by usage, error/pricing behavior, and the annotation rationale. Every sentence carries distinct information; there is no filler or repetition.

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 single-parameter read with no output schema, the description covers what is returned (confirmed and pending counts), error semantics, cost model, and the sibling alternative. An agent has everything needed to call it correctly and interpret pricing.

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?

Only one parameter and schema coverage is 100%, so the baseline is 3. The description goes slightly beyond the terse schema text ('0x address') by supplying a full example address, clarifying the expected format and checksum convention.

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 and resource ('Read the transaction count (nonce) of a 0x address on Base') plus scope ('both confirmed and including pending transactions'), which is non-obvious detail. It explicitly differentiates from the nearest sibling by naming base_balance for balances.

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?

Gives two concrete use cases ('build the next transaction', 'tell whether an address has ever sent anything') and names the alternative tool for the adjacent need ('for its balance use base_balance'). When-to-use and when-not-to-use are both covered.

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