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

Annotations already establish this is a non-idempotent, non-destructive write, so the bar is lower. The description adds genuine behavioral context beyond them: times are interpreted in the workspace timezone, and excess slots cause posting gaps. It stops short of saying what happens when a slot duplicates an existing one.

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, each doing distinct work: what it does, the timezone assumption, and the over-adding caveat. The most important constraint is front-loaded with zero padding.

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 one-parameter mutation tool with no output schema, the definition covers purpose, timezone semantics and a key failure mode. Minor gaps remain around duplicate handling and whether returned data confirms the created slots, but nothing blocking is absent.

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?

The single `slots` array is well documented internally, with dayOfWeek and hour spelled out including the 0-23 range and Sunday-first indexing. The description's timezone note largely restates the schema's own 'Hour in the workspace timezone' text, so it adds little that the schema doesn't already carry.

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?

The description opens with a specific verb-plus-resource: it 'adds recurring weekly openings to the calendar.' That is enough to separate it from list_slots, delete_slot and next_available_slot without opening a schema, though it never explicitly names those siblings.

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?

It gives real usage guidance: consult the user on posting frequency before adding slots, because over-provisioning creates content gaps. What is missing is routing against alternatives, e.g. when to use update_schedule or delete_slot instead.

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