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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so safety is covered. The description adds genuinely useful behavioral context beyond that: the data is ETF-vehicle derived, EM is approximated from country funds, and results refresh daily after each regional close — real provenance and freshness caveats.

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 core scope is front-loaded in the first clause and the paragraph is appropriately short for a read-only data tool. Some phrasing ('The decomposition institutions see', the branded opener) is denser prose than needed, but it stays within one tight block.

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 no output schema, the description does the work of describing return content — per-region and per-sector leaders/laggards across four windows — which is enough for an agent to know what comes back. It lacks any note on volume or shape of the payload, but that is a minor gap.

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 both parameters are enums with their own descriptions, so the schema carries the load. The description echoes the region and window values ('5d, 1m, 3m, ytd', 'US, Europe, Asia-Pac DM, EM') but adds no syntax or format meaning beyond the schema, making the baseline 3 correct.

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 names a specific resource (eleven GICS sectors × four regions returns) and states what is returned (returns over a window, with leaders and laggards per region and sector). An agent can grasp the tool's function immediately, but it never contrasts itself with siblings like get_ranking or compare_indices, so differentiation is left to inference.

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 is only implied: the reference to 'closelook.net/lab/sectors/' and the daily-after-close cadence hint at the context, but there is no explicit when-to-use, when-not-to-use, or named alternative among the 24 siblings. An agent must infer it is the sector-rotation decomposition tool.

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