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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds routing context (use get_area for geometry and contained places) but says nothing about what a returned area record contains or how the default limit of 20 affects results. Against rich annotations, that is an adequate but not additive level of disclosure.

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 sentences, zero filler, with the core purpose and geography front-loaded before the sibling hand-off. Every clause earns its place by either scoping the tool or routing the agent elsewhere.

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 zero-required-parameter, read-only list tool whose annotations already cover safety, the definition supplies purpose, scope, and a next-step pointer. The remaining gap is that with no output schema, the description never hints at the shape of a listed area (name, id, category, coordinates), which an agent may need to chain into get_area.

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%: limit default, multilingual query, and both enums (category, province) are already documented in the schema. The description's mention of 'shopping districts, exploring zones and water towns' loosely mirrors the category enum values without explaining filtering behavior or the 'relaxing' category. Baseline 3 applies since the schema carries the parameter burden.

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 names a specific verb ('Discover') and enumerates the exact resource types (neighborhood areas, shopping districts, exploring zones, water towns) plus the geographic scope (Shanghai, Jiangsu, Zhejiang). It also explicitly distinguishes itself from the sibling get_area, so an agent can pick between them without opening a 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?

It gives clear usage context ('when planning itineraries or choosing areas to explore') and points to get_area for exact GeoJSON boundaries and places_inside, which is a real alternative routing. It stops short of stating exclusions, such as when to prefer search_places or list_categories over this list.

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