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

Annotations already establish readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds a non-obvious behavioral default: 'Paid promotions are filtered out unless include_sponsored is set.' This goes beyond structured fields and clarifies an important hidden behavior 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?

The description is exactly two sentences with no filler. The main purpose is front-loaded, followed by a compact list of filter dimensions and a key behavioral default. Every sentence earns its place.

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 tool with 21 parameters, a rich output schema, and detailed per-parameter descriptions, the description provides adequate orientation: what it searches, which platforms, and a notable default. It could explicitly mention pagination or sorting, but those are already documented in the schema, so nothing essential is 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 the baseline is 3 and the schema already explains every parameter thoroughly. The description's enumeration of filter types adds no syntax or format details beyond what each parameter description provides. It does not need to compensate for any gap.

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 clearly states a specific verb ('Search') and a specific resource ('second-hand listings on Marktplaats or 2dehands'), and enumerates the available filter dimensions. It is not a tautology and gives a concrete sense of the tool's role. However, it does not explicitly distinguish itself from sibling tools like list_seller_listings or check_new_listings, so it falls short of a 5.

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 implies the tool is for finding listings by criteria, and the schema's parameter descriptions point to companion tools (list_categories, list_category_filters), providing indirect workflow guidance. There is no explicit 'use this when...' or 'use X instead when...' statement, so an agent must infer when to choose this over siblings.

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