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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new context: dates are 'resolved' to the next edition and each item carries starts_on/ends_on, an organiser source URL and a citation page. It does not mention rate limits or the unauthenticated 20-result ceiling, which the schema covers instead.

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 the usage trigger, then the resource, then the return shape — good ordering. The four quoted example queries take real space but each demonstrates a distinct filter combination, and the 'Filter by city, country, a date window and text' sentence is largely redundant with the schema.

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?

An output schema exists, so return values need not be enumerated, and annotations carry the safety profile. Combined with 100% schema coverage, the description supplies everything an agent needs to select and invoke this tool correctly, plus the extra 'resolved next edition' framing.

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 description coverage is 100%, so the schema already documents all six parameters including the ISO date semantics and the API-key result cap. The description's 'filter by city, country, a date window and text' restates the schema without adding format, precedence or combination rules, so the baseline 3 applies.

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 specific resource (food festivals / food events / Christmas markets) with a specific behavioural detail — the next resolved edition dates — plus filtering dimensions. The example utterances ('when is the Alba truffle fair') make it unmistakable that this is the festival-lookup tool and not the generic things_to_do or experiences 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?

Opens with an explicit trigger ('Use when the user asks what food festivals, food events or Christmas markets are on, or when one is') and follows with four concrete user phrasings that map directly onto the tool's filters (country+month, city+week, country, named event). No alternatives are named, but the trigger conditions are stated positively and unambiguously enough that an agent can route correctly.

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