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

The description adds meaningful behavior beyond the annotations: specs are re-validated against the leaf schema, return_policy against the platform statutory floor, and most valuably, buyers with pending intents are re-validated at confirm time rather than blocked here. This prevents an agent from wrongly assuming the update will fail or trigger immediate re-validation. It doesn't cover every behavior, but the additions exceed what annotations already provide.

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 sentences with zero filler: purpose is front-loaded in the first sentence, and the two following sentences add high-value behavioral context about validation and deferred re-validation. 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 15-parameter mutation with nested objects and no output schema, the description covers the purpose and the highest-risk validation behaviors well, but it omits response/return semantics and failure behavior. The partial-update semantics ('omitted fields unchanged') are only present in the schema's product_id description, not the tool description, leaving a modest gap for a complex tool.

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 schema carries the burden for all 15 parameters. The description adds value only for specs and return_policy by disclosing their re-validation rules; the other 13 parameters receive nothing beyond their schema docs. This matches the baseline-3 case for high schema coverage.

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 (Patch), resource (existing listing), and ownership constraint (the calling seller owns), which unambiguously differentiates it from siblings like seller_create_listing, seller_archive_listing, and services_create_listing. The patch semantics are immediately clear from the first sentence.

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 ownership constraint and 'existing listing' phrasing imply this is the right tool for modifying a seller's own listing, but the description never names alternatives or states when not to use it. In particular, the boundary with seller_update_stock (which also mutates listing data) is left to inference rather than explicit routing.

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