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

Annotations already declare readOnlyHint=true, so the safety profile is clear. The description adds useful behavior beyond annotations: filters combine with AND, results are paged via offset/limit, and next_offset indicates continuation.

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?

The description is front-loaded and appropriately sized, covering purpose, filtering, paging, and useful fields in a compact form. The trailing endpoint reference is minor implementation detail that slightly dilutes conciseness but does not harm usability.

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?

Given a rich parameter schema and readOnly annotation, the description provides enough context to call the tool correctly: what activities are, how filters combine, and how paging works. It does not detail result fields, but no output schema exists and the search purpose is clear.

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%, so the schema already documents all parameters. The description adds activity-specific field examples (parent_object_type, parent_object_id, type_id, system_ctime, system_created_user_id) and clarifies next_offset continuity, giving extra semantic value beyond the schema.

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?

The description states a specific verb and resource: searching activities, with a parenthetical defining activities as the log of calls, emails, and other actions on records. This clearly distinguishes it from sibling search tools such as appointments, contacts, and listings.

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?

The description implies when to use the tool by defining activities and search behavior, but it does not explicitly state when to use it versus alternatives like rex_search_appointments or rex_describe_search_fields. No exclusions or routing guidance are provided.

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