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

Beyond the annotations, the description discloses that the operation is free, that it adds 30 days, that expired listings become active again, and that pending/rejected/sold/draft listings are ineligible. These are material behavioral details that an agent needs beyond the basic mutating intent.

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?

Three tightly written sentences with no filler. The core purpose and constraint are front-loaded, and each subsequent sentence adds a distinct fact: cost, expiration mechanics, and invalid states.

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 an output schema and mutation-related annotations present, the description covers the effect, cost, expiry behavior, and prohibited statuses. Nothing essential for correct invocation 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?

The only parameter, listing_id, has no schema description (0% coverage), but the description compensates by requiring it to reference one of the user's own listings and by defining eligibility statuses. It does not explicitly mention the parameter name, but the semantics are clear and sufficient for this simple 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?

Description states a specific action (renew), a specific resource (the user's own listings), and the concrete effect (extends expiry by 30 days). It clearly distinguishes from siblings like create_listing, update_listing, and set_listing_status because renewal has unique semantics around expiry and reactivation.

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 gives clear context for when to use this tool: to renew one of the user's own active or expired listings. It also states which statuses cannot be renewed, but it does not explicitly name alternative tools or conditions where another sibling should be used, so it falls just short of a 5.

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