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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description goes further by disclosing that counts include every appointment status, that days are grouped by UTC, and that counting truncates at 100. The 100-cap is a real behavioral limit an agent would otherwise miss. It does not describe the shape of the returned summary, but an output schema exists.

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 dense sentences: the first leads with the usage trigger, the second packs scope, defaults, limits and exclusions. No wasted clauses and the most decision-relevant information (what it counts, what it excludes) is front-loaded.

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 aggregate with an output schema, the description covers everything an agent needs: when to call it, the range defaults and ceiling, the truncation cap, timezone semantics, and what it is not for. Nothing material is left unspecified.

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 the schema already documents clinicId format, ISO 8601 date-times, and the 7-day default/31-day max for the range. The description's restatement of those defaults adds little beyond the schema, with the 100-count cap and UTC-day grouping being the only genuinely new semantics. 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 and resource ('returns appointment counts per UTC day for one practice') and scopes it precisely: all statuses, 7-day default, 31-day max, 100-count cap. It also differentiates itself from the counting of cancellations or booking detail, so an agent can separate it from siblings like get_clinic_availability or list_calendar_events.

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 an explicit when-to-use trigger ('when someone asks how busy their dental practice is or how many appointments are booked each day') and an explicit exclusion ('Not for counting cancellations or seeing who is booked'). It stops short of naming the sibling tool that should be used instead, so the routing is clear but not complete.

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