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

Annotations already establish read-only, idempotent, non-destructive behavior, so the bar is lower. The description adds useful behavioral context beyond them: price_type defaults to take_home, and with no output schema present it names the return fields (take_home_usd, buyer_price_usd). It does not discuss edge cases such as invalid categories.

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?

It is front-loaded with a clear 'Use when' opener, but the Facebook Marketplace/Craigslist/OfferUp list is repeated across sentences and the seller-perspective explanation is verbose, adding some redundancy for the information conveyed.

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 computation tool with no output schema, the description usefully states the two return values and the default behavior of price_type. Combined with the required-parameter guidance ('Give category and price'), it is nearly complete, missing only error/edge-case handling.

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 75%, so the schema already carries most parameter meaning. The description largely restates the schema's price_type semantics ('Pass facebook_buyer_price when the number is what a buyer pays') and adds only the default-value fact ('price_type defaults to take_home'), leaving price_usd undocumented by both.

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 operation (quoting a cross-list price) and clarifies the two resulting numbers (take-home vs buyer price). It distinguishes itself semantically from pricing_quote_payout by centering on cross-listing to other marketplaces, though it never names that sibling directly.

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?

It gives clear triggering context: 'Use when the user is selling a large or valuable item... including when also posting to Facebook Marketplace, Craigslist, or OfferUp.' That is a strong when-to-use signal, but it names no alternative tools and gives no explicit when-not-to-use condition, so the routing is implied rather than spelled out.

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