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

Annotations already cover the read-only and open-world profile, so the description is free to add higher-value context: the data is 'indexed' sale-price history, it includes sale times plus settlement-token AND USD prices, and never-sold items return an empty points list. That empty-result edge case is genuinely useful. It stops short of noting pagination or historical coverage limits, so a 4 rather than 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?

Two sentences, zero filler, with the core action front-loaded and the disambiguation routing in the second sentence. Every clause earns its place.

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?

Output schema exists, so return values need not be described, and the description still flags the empty-points edge case. For a 3-required-param read tool this is complete.

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 chain, contract_address and token_id are already documented in the schema. The description only restates that these three identify the item and adds nothing about formats (e.g. token_id as a string, contract address casing). 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?

States a specific verb (fetch) and an unambiguous resource (one NFT's indexed sale-price history) and names the three identifying parameters. An agent can distinguish it from opensea_item_listings/offers/activity and opensea_collection_chart without opening any 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?

Explicitly routes the agent: use listings/offers/activity for current orders and events, and collection_chart for collection-level trends. The condition selecting this tool (per-item historical sale prices) is implied by contrast with those alternatives.

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