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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds useful semantic context by clarifying that the result counts active listings and is an inventory count rather than a valuation.

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 two short sentences, with the trigger front-loaded and no filler. Each sentence adds distinct value: one gives the usage condition, the other clarifies the result type.

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?

While annotations and output schema cover safety and return shape, the tool has 24 optional parameters with low schema coverage, and the description gives no guidance on how to choose or combine them. An agent would struggle to identify which filters to populate for a given user request.

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?

With 24 parameters and only 4% schema description coverage, the description carries the burden of explaining parameter roles, but it provides no parameter-level guidance beyond the generic phrase 'explicit filters'. This leaves nearly all parameter semantics undocumented and uncompensated.

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 identifies a count of active listings with explicit filters, using a specific verb and resource. It distinguishes the tool from a market valuation, but it does not explicitly name or contrast sibling tools, so it stops short of full differentiation.

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 opening phrase 'Use this when the user asks how many active listings match explicit filters' provides a clear trigger condition. It also offers an exclusion ('not a market valuation'), though it does not mention alternative tools by name.

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