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 genuine behavioral context beyond that: each sample is returned in both the settlement token and USD, and the metric choice changes the chart form. It doesn't discuss pagination or rate limits, so it falls short of a 5.

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?

Front-loaded with the core purpose and the sibling routing, and every sentence is functional. Slight redundancy in repeating the metric and timeframe enumerations that already live in the schema keeps it from a 5.

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, return-value detail is not required, and the description covers scope, metric selection, timeframe, and the sibling alternative. Nothing essential for a correct call is missing, though it could note settlement-token variability more precisely.

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 the schema already documents slug, metric, and timeframe. The description largely restates the same enum values and defaults verbatim, adding no syntax or format detail beyond what the schema provides. Baseline 3 is 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?

States a specific verb and resource ('Returns a time series for a collection') plus the exact measures available (floor price or traded volume). It explicitly contrasts itself with the sibling opensea_item_chart, so an agent can select between collection-level and item-level charts without opening either schema.

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 routing: 'Use metric=floor_price for the floor line and metric=volume for the volume bars' and 'Use opensea_item_chart to get an OpenSea NFT's sale-price history'. The when-to-use and the alternative are both stated explicitly.

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