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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds one genuinely useful behavioral caveat — that some events are only visible in the FUB app, implying results may be incomplete relative to the UI — plus the underlying endpoint, but says nothing about pagination limits or response shape.

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?

Three short fragments with no filler, and the core purpose is front-loaded before the caveat and endpoint. Slightly telegraphic, but every sentence carries information.

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, zero-required-parameter list tool with 100% schema coverage and no output schema, the description covers purpose, filterable dimensions, and the notable 'app-only events' caveat. The missing piece is any hint about the shape or pagination of the returned event list, which the absence of an output schema leaves unstated.

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 all seven parameters are already fully documented in the schema, including the next/offset preference and the event-type enumeration. The description only echoes filtering by person or type, adding no syntax or format detail beyond the schema, so the 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 (list) and resource (lead events) and enumerates concrete event kinds (registrations, inquiries, viewed/saved properties, website visits), which is more than a restatement of the title. It does not distinguish itself from the sibling fub_send_lead_event or from other list tools like fub_list_calls, so it stops short of a 5.

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?

"Filter by person or type" describes how to narrow results but not when to choose this tool, which is guidance that belongs to the schema anyway. There is no statement of when-not-to-use it or what alternative sibling covers a related need (e.g., fub_list_calls for call events, fub_send_lead_event for writes).

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