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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds provenance (this is Alt's own index, a subset of the site's data) and enumerates the returned metrics, but those returns are also captured by the existing output schema, so the added behavioral value is modest.

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?

A single front-loaded sentence with the data source and returned fields, using an em-dash clause efficiently. No filler, though it spends words restating the site-page equivalence.

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 and annotations covering safety, the description only needs to convey scope and provenance, which it does. The one remaining gap is that it never routes the agent to the correct sibling tool for card-level or mover data.

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 single optional 'category' parameter is documented thoroughly in the schema, including the exact-match constraint and omit-for-all behavior. The description adds nothing param-specific beyond that, so the baseline of 3 applies with a slight bump for reinforcing the per-category granularity.

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 ('Alt's own category-level price-trend index') and its granularity ('per card category'), which lets an agent separate it from card-level siblings like alt_top_movers or alt_card_search. It is a noun phrase rather than an explicit verb+resource, and it never names the alternative tools, so it stops short of a 5.

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 same data alt.xyz's Market Trends page shows' hints at when this index is the right source, and the schema's category note tells the agent to omit the filter for all categories. There is no explicit when-to-use, when-not-to-use, or named alternative such as alt_top_movers.

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