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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely new behavior: a cap of 5 results ordered nearest-first, per-result freshness metadata (organizer page checked, check date, expiry date), a possibly-unannounced date state, and a staleness warning telling the agent to redirect users to the organizer. It does not mention auth or rate limits, but none appear relevant.

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?

Purpose and scope are front-loaded, and the exclusions land at the end where they are easy to scan. The middle sentence enumerating every returned field is long and partly redundant with the output schema, which is the only real source of bloat.

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 an output schema present the description does not need to explain return values, yet the enumeration of freshness fields (checked date, expiry date) is the key detail for trusting results. Coverage, radius, date window and the sibling boundary are all addressed, leaving nothing an agent needs missing.

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 the 'place' formats, the YYYY-MM-DD dates, the 120-day range limit and the 5-250 mile radius is already documented. The description adds only light framing (US places, 2026 season, 'optionally on certain dates'), which is marginal beyond the schema — baseline 3 is appropriate.

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 verb and resource ('where and when Christmas markets ... are near a US city, state or ZIP code'), including the aliases (Christkindlmarkts, holiday and craft markets) an agent may need to match. It explicitly distinguishes itself from the sibling find_christmas_lights_and_tree_farms, so no schema-diving is needed to route.

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?

Gives both when-to-use (someone asks where/when markets are near a US place, optionally on 2026-season dates) and explicit when-not-to-use (not for exhaustive lists, non-US markets, tickets/lodging, or lights and tree farms), naming the alternative tool for the last case.

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