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

Annotations declare readOnlyHint=true and openWorldHint=true, covering the safety and open-world profile. The description adds the scope constraint (marketplace-wide vs entity-scoped), which is useful, but doesn't cover pagination behavior or result freshness. With annotations carrying the main behavioral burden, this is adequate.

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 scope definition followed by the alternative routing. Every sentence earns its place with no redundancy.

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?

For a read-only feed tool with full schema coverage and an output schema present, the description covers what an agent needs to select the right tool and avoid the entity-scoped alternatives. Only minor gaps remain around pagination/freshness semantics.

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 coverage is 100% with detailed descriptions for limit, cursor, and event_types including allowed values. The description adds no parameter details beyond what the schema provides, so baseline 3 is appropriate.

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 resource (OpenSea's marketplace-wide activity feed across collections), and explicitly distinguishes itself from the three sibling activity tools by naming them and describing what they do differently.

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?

Provides explicit when-to-use guidance: use this tool for marketplace-wide activity, and use opensea_collection_activity, opensea_item_activity, or opensea_profile_activity to narrow to one entity. The alternative routing is unambiguous.

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