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

Annotations already cover safety (readOnlyHint=true), so the description earns credit for adding real behavioral context: the response is cached by Breeze and may lag up to 15 minutes, and enabling 'schedule' silently changes the payload to an array of {id, start} only. It stops short of describing pagination or error conditions for an invalid instance_id.

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 compact sentences plus the underlying API endpoint; the core fetch behavior is front-loaded and the conditional series behavior follows. No filler.

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?

With no output schema, the description usefully discloses caching staleness and the alternate response shape. It could go slightly further on what details/eligible add to the output, but for a single-instance read tool it is largely 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 coverage is 100%, so baseline is 3, but the description adds genuine meaning the schema does not: it clarifies that the response shape degrades to {id, start} only when series instances are requested, which agents need to know before setting schedule. The interactions among schedule, schedule_limit, and schedule_direction remain implied rather than spelled out.

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 concrete verb and resource ('Fetch one event instance') plus the optional series-expansion behavior, which clearly separates it from the sibling list tool breeze_list_events. An agent knows exactly what this returns without opening the 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?

Usage is implied: fetch a single instance by id, and the 'schedule' flag is explained in terms of effect. However, there is no explicit when-to-use guidance versus breeze_list_events, nor any stated prerequisites or exclusions.

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