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

Annotations only declare readOnlyHint and openWorldHint=false, so the description carries the real burden and does it well: it explains that spaces_left appears only when a class is nearly full (absence means availability), that full and waitlist_open mark a closed class, and that a book_url accompanies each entry. These are non-obvious data semantics an agent could easily misread from field names alone.

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?

Four short sentences, front-loaded with the resource and its contents, followed by availability semantics, coverage, and the time horizon. Every clause adds information; nothing restates the tool name or title.

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 must stand in for return values, and it does so by naming book_url, spaces_left, full, and waitlist_open. It does not state the default date behaviour or result volume, though the schema covers the defaults, so the gap is minor for a read-only listing tool.

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 the baseline is 3; the description earns above that by adding an interpretive example for class_name (matching 'hot' returns hot yoga) and by stating the 14-day horizon, which gives meaning to the end_date bound that the schema only describes mechanically.

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 names a specific resource (class schedule) and enumerates the fields returned: what is on, where, when, who is teaching, and a book_url. It also scopes the offering types (yoga, hot yoga, Pilates, Reformer, barre, meditation) across all four studios, which lets an agent separate it from sibling tools like yoga_dublin_teachers or yoga_dublin_prices without opening a 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?

It gives concrete usage context: a 14-day forward window and an explicit filter example ('class_name=hot' for hot yoga). What it does not do is name an alternative and say when to prefer it — with a sibling literally called yoga_dublin_classes, the boundary between the two is left to inference.

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