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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful context beyond that: the payload shape (composite score, regime label, component contributions, pagination, data_quality metadata) and the access model ('free, no API key required'), which is not derivable from annotations.

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?

Three short sentences, front-loaded with what is returned and followed by applicability and access constraints. Dense but every clause carries information; the only mild redundancy is enumerating return fields when an output schema already exists.

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?

Given an output schema exists, the definition need not explain return values, yet it still signals the key payload components and the no-auth access model. For a zero-required-parameter, read-only analytical tool this is sufficient context to call correctly; the only gap is the absence of routing guidance versus sibling regime/rate tools.

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 schema itself documents view/series-vs-changes semantics, pagination.next_after_sequence round-tripping, limit defaults, and inclusive date formats. The description only alludes to 'pagination' generically and adds no parameter-level meaning beyond the schema, so the baseline of 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?

States a specific resource and verb: 'Return the global risk-on/risk-off sentiment series used for FX regime analysis,' and the derived composite score and regime label further pin down what the payload is. It does not name any sibling tool, so an agent cannot distinguish it from regime-adjacent tools like macro_regime_classifier_task or rate_differentials purely from this text.

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 concrete usage context – cross-asset regime context for high-beta, safe-haven, commodity, or USD-defensive FX conditions – which tells the agent what kind of question this tool answers. There are no explicit exclusions or named alternatives for when *not* to use it, which keeps it below a 5.

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