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

Annotations already mark the tool as read-only, so the description's main contribution is mode-specific behavior: slots returns start times, sessions returns classes with seats left, and period checks from/to and units left. It adds useful behavioral context beyond the annotations, though it omits response shape, pagination, and error behavior.

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 sentences with no filler: the first states scope, the second packs three mode behaviors into a readable semicolon list, and the closing directive tells the agent when to prefer this tool. Every sentence earns its place.

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 7-parameter tool with no output schema, the description gives useful mode-level expectations but omits how modes are selected, the role of party_size, and return-shape details. It is workable for a straightforward query but not fully self-sufficient.

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 descriptions already cover from/to, qty, options, and resource_id, and the description adds mode semantics that clarify qty and from/to in period mode. However, it never explains how a caller selects a mode, nor does it describe the purpose of party_size and offering_id, leaving two schema-undocumented parameters unsupported.

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 clearly identifies an availability query for a single offering and enumerates three modes with concrete return content: start times, classes with seats left, and units left. It stops short of a 5 because it does not name a sibling tool to differentiate against, only contrasting with 'guessing from opening hours.'

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?

The line 'Always call this instead of guessing from opening hours' gives a strong, explicit directive about when this tool is the source of truth for availability. However, it does not explicitly state when not to use it or mention alternative sibling tools such as owner_get_schedule or search_businesses.

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