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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description goes beyond them with genuinely useful disclosure: the data is checked live against the BLS Public Data API, and on failure it reports that and falls back to bundled data current through September 2026. A caller therefore knows results can be stale or degraded and that the failure is surfaced rather than silent.

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 sentences, front-loaded with the resource and the returned figures, followed by the usage cue and the fallback caveat. The enumerated field list is long but each item is a distinct return value, so it earns its space; the parenthetical clarifications are slightly wordy but not padded.

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?

There is no output schema, so the description must carry the return-value burden, and it does so by naming each figure the response contains. What is missing is any sense of the response's shape or ordering, and the fallback date bound ('through September 2026') leaves it to the agent to judge staleness.

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?

The tool takes no parameters, so there is nothing to disambiguate and the baseline of 4 applies. The description does not waste words inventing parameter 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?

A specific verb and resource ('Returns the most recent CPI index values published by the BLS') followed by an explicit inventory of what comes back: latest month, 12-month rate for CPI-U/CPI-W/core, NSA 1-month change, YTD change. It implicitly separates itself from get_inflation_rate via the 'inflation right now' framing, but never names a sibling or states the boundary 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?

Gives a clear when-to-use rule: 'Use it to answer what is inflation right now.' That is a concrete selection cue rather than vague framing. It offers no when-not condition and does not name calculate_inflation or get_inflation_rate as alternatives for other shapes of question.

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