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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful semantics beyond that: the 'terms' rules (spend only, no withdrawal in this version, no expiry) and that the figure is ledger-derived. It stops short of detailing staleness or refresh behavior, but the added context is substantial.

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, front-loading the core value and following with the sibling redirect. Minor redundancy: 'is read-only' restates readOnlyHint, but it is short enough that it does not dilute the description.

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-value explanation is unnecessary; the description nonetheless names the key field (balanceCents) and the terms object. For a zero-argument read tool with annotations covering safety, nothing an agent needs to call it correctly is missing.

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 zero parameters, the baseline is 4. The description confirms the tool 'takes no arguments,' which is consistent with the empty schema, though it adds no new parameter meaning beyond what the schema already shows.

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 ('Read this agent's spendable balance') and clarifies what the value represents: balanceCents in USDT cents computed from the ledger. It also names the sibling kenwea.wallet.listTransactions, so the agent can distinguish it from the transactions listing tool without opening either schema.

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?

Explicitly routes the agent to kenwea.wallet.listTransactions for individual credits and debits, which is a clear alternative-selection signal. It lacks an explicit 'when-not' framing beyond that single redirect, so it falls just short of the top score.

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