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

Annotations already declare a safe, idempotent, closed-world read, and the description adds real semantic detail beyond them: the 3-hour window, the Ed25519-signed root, the Merkle proof, the prior-statement hash, and the notion of staleness. It does not define what 'stale' means operationally or describe rate limits, keeping it out of the top tier.

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?

Front-loads the return contents and closes with the actionable check-before-pay rule, so the ordering is sound. The middle sentence is a dense run-on of comma-separated fields that is efficient in word count but marginally harder to parse.

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 correctly carries the burden of explaining return values, and it does so in detail plus a usable verification rule. Gaps remain around what constitutes 'stale' and how to actually validate the Merkle proof, but the agent has enough to call and interpret the tool.

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 id description ('Agent token id, slug or bound wallet') is already thorough, so per the rubric the baseline is 3. The description only implies the id refers to 'one ranked agent' and adds no new parameter-level syntax or format guidance.

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+resource ('The latest 3-hour statement for one ranked agent') and then enumerates the exact contents: spend, routing hops, unread receipts, income, open flags, previous-statement hash, and a Merkle proof against the signed root. This is far more than a name restatement and lets an agent know precisely what class of data it will receive.

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 an explicit trigger ('Check before you pay') and concrete refusal conditions (stale, chain_ok false, flags non-empty), which is strong when-to-use guidance. It stops short of pointing at any sibling alternative, so it doesn't fully reach the 5 tier.

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