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 that the record includes traits, owner, best listing, and best offer, but since an output schema exists this return-value detail is largely redundant; it discloses nothing about freshness, caching, or null/absent-listing behavior.

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, front-loaded with the identifier keys, second sentence devoted to sibling routing. No filler.

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 annotations covering safety, an output schema covering the record shape, and 100% parameter coverage, the description supplies everything an agent needs to select and call the tool. Only marginal gaps (e.g. what happens when no owner or best listing exists) remain.

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 all three parameters are required and documented, so the schema carries the burden. The description only restates the parameter concepts without adding format or constraint detail beyond the schema (e.g. how 'chain' values are named).

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), resource (one OpenSea NFT record), and the exact identity triple (chain, contract, token ID). This distinguishes it cleanly from sibling collection-level and search tools.

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 to opensea_item_listings and opensea_item_offers for 'the corresponding market side', which is a concrete when-to-use alternative. It does not address when to prefer this over collection- or profile-level item listings, but the routing given is precise.

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