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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and the description's '(read-only)' is consistent rather than contradicting. It adds genuinely useful behavior beyond the annotations: results are resolved to the next edition with starts_on/ends_on, plus an organiser source URL and a page to cite, which tells the agent the data is citation-ready and date-resolved.

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-loads the usage trigger, then the capability, then the return shape — a sensible ordering with no filler prose. Minor redundancy: '(read-only)' and the date-window phrasing echo annotations and schema, and the quoted example list is long, but each element is functional.

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 six-parameter, zero-required search tool with an output schema and full annotation coverage, the description supplies everything the agent needs: when to call it, what dimensions it filters on, and that dates are pre-resolved to the next edition. Return-value detail is extra rather than required, since the output schema exists.

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 every parameter including city, country, date_from/date_to semantics, and the limit/API-key cap is already documented in the schema. The description only paraphrases the filter set ('city, country, a date window and text') without adding format or interaction details such as country being optional where city is given. 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 / Christmas markets) with clear capability: 'Food festivals with their next resolved dates' and 'Filter by city, country, a date window and text.' The domain is clearly distinct from siblings like things_to_do, experiences, and tickets, so an agent can route 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?

Opens with an explicit trigger ('Use when the user asks what food festivals, food events or Christmas markets are on') and supplies four realistic user phrasings that map directly to invocation contexts. There is no explicit when-not guidance or naming of an alternative tool to use instead, which keeps it from a 5.

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