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

With only readOnlyHint=false available, the description carries real weight and delivers: photo formats (https URL or base64), the 8-photo cap, automatic GPS stripping, the consequence that photo-less listings stay private, and the first-call return of an api_key plus management link. It does not cover idempotency or auth-failure behavior, keeping it below 5.

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?

Four short sentences, each carrying distinct information, with the photo constraints and the privacy rule front-loaded ahead of the api_key return note. The leading '上架二手商品' slightly restates the title, a minor redundancy.

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 an 11-parameter creation tool with no output schema and only 45% schema description coverage, the description covers the highest-risk areas (photos, visibility, api_key return) but leaves several optional fields and the overall response shape unexplained. Adequate but visibly incomplete.

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 45% across 11 parameters, so some compensation is expected. The description adds genuinely new semantics for the undocumented photos parameter (accepted formats, GPS removal) and surfaces the api_key output, but says nothing about title, location, quantity, condition, or the free-text description field, leaving half the surface undocumented in both places.

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 opening line states a specific verb+resource (listing a second-hand item) that maps cleanly to create_listing and is distinguishable from update_listing / add_listing_photos by its creation framing. It does not explicitly name a sibling it is not, so it stops short of a 5.

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?

Usage is only implied: the note that the first call returns an api_key and management link hints this is the entry point for a new account, but there is no explicit when-to-use-this-vs-update_listing or when to attach photos here versus via add_listing_photos. The 'no photos means not public' note is a visibility rule, not routing guidance.

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