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

Annotations only say this is a non-read-only, non-destructive, non-idempotent mutation; the description adds the actual effect (expiry reset to 30 days from now), the cost profile (free, no credit charge), and the state-transition rules. That is substantive behavioral context beyond the structured hints, including which listing states will fail.

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?

Front-loads the action and ownership scope, then cost, then eligibility in descending priority. Every clause carries distinct information with no repetition of the name or annotations.

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?

With an output schema present, return values need not be explained, and the key preconditions and side effects are covered. Minor gaps remain: no mention of auth/permission requirements or what happens on a repeated renewal given idempotentHint=false.

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 coverage is 100% and the single listing_id parameter is already documented with provenance (search_listings, semantic_search, list_my_listings) and an example. The description adds nothing about the parameter itself, so the baseline 3 applies.

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?

States a specific verb (renew), a specific resource (a listing), and scope (one of the USER'S OWN listings), which separates it from update_listing or set_listing_status in the sibling set. The parenthetical about native listings lapsing ~30 days after posting explains what renewal means mechanically.

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?

Gives explicit eligibility rules: expired listings return to active, while pending, rejected, sold, or draft listings cannot be renewed. It does not name alternative tools (e.g., set_listing_status) for those ineligible states, so the agent must infer the fallback.

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