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

readOnlyHint=true already declares this a safe read operation, so the bar is lower. The description is consistent with that and adds the underlying REST endpoint, but discloses nothing further about rate limits, pagination, or whether empty days return an empty list versus an error.

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 short, front-loaded sentences with no filler. The trailing REST endpoint note is mildly useful for orientation but does not help an agent select or invoke the tool.

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 simple read-only 4-parameter tool with full schema coverage and annotations, the description covers what the tool does and the scoping constraints. With no output schema, a hint at the return shape exists ('time slots'), though its format is left unstated.

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 the baseline of 3 applies. The description restates the date and appointment-type scoping already documented in the schema, and says nothing about timezone or calendarID, adding no meaning 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 ('List available time slots') scoped by date and appointment type, so the agent knows what it returns. However, it does not distinguish itself from its closest siblings acuity_availability_dates and acuity_availability_classes, which also return availability data.

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?

No guidance on when to use this versus acuity_availability_dates or acuity_availability_classes, nor any prerequisites or exclusions. Usage is only implied by the word 'availability' in the name and description.

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