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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), so the description's job is to add semantics — and it does: spending on assess_remaining or verify_remaining draws from one shared balance rather than separate allowances, and verify_claim is an order of magnitude more expensive. Those are non-obvious behavioral facts an agent could not infer from annotations or schema.

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-loaded with the purpose and the single-pool model, and each paragraph builds on the last. It is on the long side for a zero-parameter tool — the cost_options.verify.depth.low path example is quite specific — but that detail is genuinely needed to interpret 'what credits buy.'

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 no-argument tool with an output schema and full annotations, everything an agent needs is present: when to call, when not to, how the balance is shared, and how to price the expensive sibling before batching. Nothing material is left to inference.

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?

Zero parameters, so the baseline is 4. The description spends its words on output-shape guidance instead (costs keyed by capability, cost_options nested capability → parameter → value), which is partly redundant since an output schema exists, but it usefully flags that prices are live and should be read rather than assumed.

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 verb and resource — shows remaining Lenz credits and what they buy — with the awkward-but-useful framing that a single pool funds all calls. It also implicitly distinguishes itself from spending tools (verify_claim, assess_claim, ask_followup) by positioning itself as the budget-inspection counterpart.

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 explicit triggers (user asks about credits, or before a large batch to size against credits_remaining) and an explicit exclusion: 'It is not a prerequisite: never call it before an ordinary check.' That negative guidance directly prevents over-calling, which is the main risk with a zero-cost-looking usage tool.

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