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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still adds real behavioral detail the annotations cannot: UTC-day bucketing, status-agnostic counting, a 7-day default with a 31-day maximum, and a silent truncation cap at 100 counts. It does not, however, explain what happens when the cap is hit (partial day? error? omitted days).

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 sentences, each doing distinct work: usage trigger first, then output/behavior bounds, then exclusions. No filler and the most decision-relevant information (when to reach for it) 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?

An output schema exists, so return shape need not be described. For a three-parameter read with full schema coverage, the description supplies everything an agent needs to select and call it correctly: the trigger, the date-range bounds and the sibling-excluding boundaries.

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 startTime, endTime and clinicId are all documented in the schema itself; the baseline is 3. The description restates the default window and the 31-day ceiling, which is consistent with the schema but adds no syntax or format information beyond it.

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 fixes the scope to a single practice and a bounded date window. It is readily distinguishable from siblings like list_calendar_events or show_clinic_overview, which return events or aggregate summaries rather than per-day counts.

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?

Opens with an explicit trigger ('Use this when someone asks how busy their medical practice is or how many patient visits are booked each day') and closes with an explicit exclusion ('Not for counting cancellations or seeing which patients are booked'). Both the when and the when-not are handed to the agent with no inference required.

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