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

Annotations already cover safety (readOnlyHint, destructiveHint) and open-world scope, so the bar is lower. The description still contributes real behavior: result ordering (soonest first), structured date/venue fields, no auth requirement, and the key limitation that city filtering is not server-side but must be done on `event.city_normalized` after the call.

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?

Front-loaded with purpose, then sibling routing, then prerequisites and the post-filter caveat — a natural priority order. Dense but every clause carries information an agent would otherwise have to discover by trial.

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 6-param optional-everything query tool with an output schema and full annotation coverage, this supplies the missing pieces: ordering semantics, sibling disambiguation, auth cost, and the one behavioral trap (no city filter). Return-value shape is rightly left to the output schema.

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; the description goes slightly beyond it by naming the filter dimensions (kind, genre, topic, date range) and by revealing that city is deliberately NOT a parameter and must be applied client-side to `event.city_normalized`. It does not restate enum values or limit bounds, which the schema already carries.

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?

Specific verb+resource ('Find upcoming events') with the domain enumerated (concerts, gigs, meetups, conferences, festivals), plus result ordering ('soonest first') and the filter axes. It also explicitly distinguishes itself from the sibling get_latest, so an agent can pick between them without opening either 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?

Explicit when-to-use ('Use this for anything about events') and when-to-use-alternative ('use get_latest with product=events only for a raw newest-first scan'). It adds an operational prerequisite ('Needs no API key') and a workaround for an unsupported filter (city), leaving nothing to inference.

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