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

Annotations already declare readOnlyHint=true, so the description is free to spend its words on the pagination contract (offset/limit with next_offset as the continuation token) and the AND-only combination rule, which the annotations do not cover. It stops short of describing result row shape or behaviour on invalid field names.

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-loaded with the resource and its clarification, then pagination, then field discovery. Every sentence carries a distinct fact and nothing repeats the schema verbatim.

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 five-parameter nested search tool with no output schema, the description covers the mutation/safety stance (via annotations), the AND semantics, the paging loop including how to continue, and where to get valid field names. An agent can construct a correct call and page through results without guessing.

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 baseline is 3, but the description adds genuinely new parameter-level guidance: which service to pass to rex_describe_search_fields to discover legal `criteria.name` values and the fact that searchable fields mirror Reminders (reminder_date, remindee_user_id, contact_id, property_id, listing_id). That is information absent from 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?

States a specific verb (Search) and resource (appointments) and clarifies the ambiguous term as "calendar items such as inspections and meetings", which an agent could not infer from the name alone. It does not, however, explicitly distinguish itself from near neighbours like rex_search_reminders or rex_search_activities, so the sibling boundary is only implied.

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?

Gives clear operational context: filters combine with AND, results are paged, and field names must come from rex_describe_search_fields with service Appointments. It does not state when to prefer this over rex_search_reminders or rex_search_activities, so there is no explicit exclusion or alternative routing.

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