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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered structurally. The description adds genuinely useful behavior beyond that: an item with no active offers returns an empty list rather than a 404, which prevents an agent from misinterpreting an empty result as an error.

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-loads the core purpose and the empty-list edge case, then the routing hint. The two sentences echoing schema parameter text ('chain: ... Required.') are redundant filler, but overall it is tight and well-ordered.

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?

An output schema exists, so the return contract need not be spelled out, yet the description still names the fields. The no-offers edge case and the sibling routing are covered; only the non-required filtering params (event_types, sort_direction) lack any narrative context.

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 all seven parameters. The description only restates chain and contract_address verbatim from the schema and omits token_id, limit, cursor, event_types, and sort_direction, adding no meaning beyond the structured fields. Baseline 3.

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 every standing bid on one NFT') and enumerates the returned fields (price, quantity, validity window, marketplace, maker's wallet). It is clearly distinguishable from the sibling opensea_collection_offers, which operates at collection scope.

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 names the alternative tool ('Use opensea_collection_offers to list an OpenSea collection's offer book') and the condition that selects it, so the agent can route item-level vs collection-level offer queries without inference.

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