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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is covered. The description adds real behavioral value beyond them: rows are official-source headlines with 'lightweight keyword-derived' affected_indicators and sentiment only 'when a headline is classifiable' (a quality caveat), and non-USD currencies return subscription_required with a subscribe link. Rate limits and pagination behavior are the only notable omissions.

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?

The output shape is front-loaded in the first sentence, followed by the row-quality caveat, then the currency/access constraint. The long middle sentence enumerating eight narrative categories is somewhat dense, but every clause carries usable information and nothing is padding.

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 an output schema present, the description needn't explain return values, and it covers the essentials: what the rows are, the currency format, and the paywall behavior that changes how an agent must handle a non-USD response. It is close to complete for a read-only, four-parameter lookup; only sibling differentiation 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?

Schema description coverage is 100%, so all four parameters are already documented in the schema, including limit, offset, currency and lookback_days. The description restates the currency format ('lowercase 3-letter catalogue currency') which duplicates the schema rather than adding new meaning, so baseline 3 applies.

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?

The description gives a specific verb and resource: 'Return recent official central-bank news and press-release headlines for a currency,' and enumerates the narrative topics covered (policy, inflation, employment, GDP, trade, fiscal, energy, commodities). It is clear what the tool returns, but it never names the adjacent siblings (press_releases, latest_announcements, geopolitical_event) that an agent might otherwise confuse it with.

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?

Usage context is only implied by 'for a currency' plus the topic list, and the access rule (USD free, other currencies subscription_required) is a strong practical signal. There is no explicit statement of when to prefer this over press_releases or latest_announcements, and no exclusion guidance, so the agent must infer the boundary.

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