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

Annotations already declare readOnly, idempotent and non-destructive behaviour, so safety is covered. The description's added value is the disclosed output structure (day groupings, transit hops, leftover sights), which matters because there is no output schema. It says nothing about response size, cost, or how bounds like the 7-day cap affect results.

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?

Two tight sentences: the output contract first, an illustrative example second. No filler, no repetition of the title, and the most decision-relevant information is front-loaded.

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 10-parameter generative planning tool with no output schema, the description does well on return shape but skips the mechanics that would help: how days, hours_per_day and start_weekday interact (closed-day avoidance is only in the schema), and what happens when a city has too few sights for the requested duration. Adequate but incomplete.

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 70% and enums are self-documenting, so the schema carries most of the load. The description names no parameter at all — not days, pace, style, interests, periods, start_weekday — so it adds nothing beyond the structured fields and leaves the three undocumented params relying solely on the schema.

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 states the resource concretely — a multi-day plan for a single city — and even sketches the output shape: days built around one or two walkable areas linked by a transit hop, ordered as walking routes, with leftover sights appended. That is enough to tell it apart from plan_walking_tour and recommend_attractions, though no sibling is named explicitly.

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?

The example query ("three days in Vienna for art and music lovers") implies the intended use case, but there is no explicit when-to-use/when-not guidance and no routing to alternatives such as plan_walking_tour or get_city_guide. The agent must infer that this is the multi-day planning entry point.

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