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

Annotations only say readOnlyHint=false and destructiveHint=false; the description adds substantial context beyond that — it writes to the live account, it cascades into invoice, clinical note and reminder creation, and a conflict returns HTTP 409 with nothing created. That last point is the crucial behavioral guarantee (atomic failure) an agent needs before retrying.

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?

Five short sentences, no filler. The write-to-live-account warning is front-loaded and each subsequent sentence adds a distinct fact: side effects, the discovery sibling alternative, and conflict behavior.

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?

Covers mutation risk, cascade side effects, error semantics and the prerequisite lookup tool — strong for an 8-parameter mutation tool with no output schema. The one gap is that it never says what the call returns (presumably the created appointment id), which matters since there is no output schema to fall back on.

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% and every parameter already carries a description, including defaults for status and fail_on_double_booking, so the schema does the heavy lifting. The description's mention of practitioner role as practitioner-at-a-clinic and the default double-booking refusal reinforces but does not add syntax or format detail 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?

States a specific verb and resource ('Books an appointment') and names the three key entities (patient, practitioner role, clinic). It also distinguishes itself from the sibling that only reads availability, so an agent can route between them without opening either schema.

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?

Explicitly routes the agent to halaxy_find_available_appointments 'for free times', which is the main prerequisite for booking. It stops short of stating when not to book (e.g. rescheduling an existing appointment, or using halaxy_update_appointment_status for status changes), leaving that inference to the agent.

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