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

Annotations only supply destructiveHint=true; the description adds real context beyond that by disclosing the mutation target ('MODIFIES the calendar'), the email side effect with its suppression caveat, and the underlying REST call. It stops short of stating whether availability is validated or what happens on slot conflict, but the safety-relevant behavior is well surfaced.

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 short sentences, front-loaded with the core action, then side effects, then the API mapping. No filler and nothing buried.

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 12-parameter mutation with a fully documented schema and no output schema, the description covers purpose, mutation scope, and side effects adequately. It could say more about prerequisites (e.g., that a valid appointmentTypeID and open slot are needed, or that admin=true skips availability checks), but nothing critical is missing.

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 all 12 parameters are already documented in the schema (including admin's bypass semantics and noEmail's suppression behavior). The description's 'unless suppressed' phrase adds only marginal gloss over what the schema states, so 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 ('CREATES a new appointment') and immediately disambiguates with 'books a client into a time slot', which is not obvious from the name alone. The sibling tools (cancel, reschedule, get, list) are all distinct operations, and this description makes clear it is the creation path.

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?

Usage is implied rather than stated: the agent can infer this is the tool for booking a new slot, and 'unless suppressed' hints at the noEmail control. However, there is no explicit when-to-use guidance relative to alternatives such as acuity_reschedule_appointment (for moving an existing appointment) or acuity_create_client, so routing must be inferred from the name.

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