Compare several Hemnet listings

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

Beyond the annotations (readOnly, openWorld, idempotent), the description adds meaningful behavioral constraints: up to 20 targets, input order is preserved, per-row errors are captured, and the operation is read-only. This gives the agent useful execution expectations without contradicting the annotations.

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 convey purpose, accepted input format, cardinality, ordering behavior, error handling, and read-only nature. Every clause earns its place and the most important info 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 single-parameter tool with rich annotations and a fully documented schema, the description covers the key operational details: what it does, what inputs it accepts, limits, order preservation, and error behavior. No critical gap prevents correct invocation.

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?

The schema fully documents the ids parameter, so the baseline is 3. The description adds value beyond the schema by stating that input order is preserved and that each row can have its own captured error, which affects how the agent should interpret the array parameter and results.

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 a specific verb ('fetch and normalise') and a specific resource ('multiple active for-sale Hemnet listings'), and clarifies the purpose: side-by-side comparison. This clearly distinguishes it from single-listing siblings like hemnet_get_listing and sold-listing tools like hemnet_get_sold_listing.

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 description makes the intended context explicit: use it when you need multiple active listings at once for comparison. It does not explicitly name sibling alternatives or state when not to use it, but the context is clear enough for an agent to select it appropriately.

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