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 a genuinely useful caveat that some events are only visible in the FUB app (a data-completeness limitation), but it says nothing about pagination constraints or how the result is scoped beyond that note.

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 short sentences plus an endpoint reference, with the core resource defined up front and no filler. Efficient and front-loaded, though the endpoint reference is redundant rather than additive.

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 list tool with full schema coverage, no required params, and no output schema, the description conveys what is returned and how to filter it. The app-visibility caveat closes the main completeness gap; missing return-shape detail is acceptable since no output schema exists and results are self-describing.

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 each of the 7 parameters is well documented in the schema (including the full event-type enum and cursor guidance). The description's "filter by person or type" only gestures at personId/type, adding no syntax or meaning beyond the schema, so 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 resource (lead events / lead activity) with concrete examples of event types, and the endpoint reference (GET /v1/events) confirms the read-list semantics. It is clearly distinguishable from siblings like fub_list_calls and fub_list_tasks, though it never names those alternatives.

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" implies a usage pattern but gives no explicit when-to-use/when-not guidance or routing to siblings (e.g. fub_search_people or fub_list_calls). Usage context is present but left to inference.

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